feat(frontend): 图表层从 echarts 迁移 layerchart（新长格式 Chart API）

[变更性质]
图表渲染引擎替换，渲染输出保持同等信息（曲线/图例/轴），删除
echarts 在后续页面迁移后正式退场。

[新增功能]
新 Chart.svelte 封装 layerchart LineChart，API 为长格式 data（
{i, date, ...columns}）+ series（key/label/value/color/dashed/area）。

[实现方案]
宽度语义与旧 echarts 包装一致：ResizeObserver 实测宿主宽度优先，
width prop 只是初始/测试尺寸，640 为无布局回退——SVG 永远跟随宿主，
绝不粘滞桌面宽度。runes 模式的关键坑：measured 必须 $state，否则 RO
回调触发的宽度更新不会重渲染（旧 echarts 版本为命令式 API 无此问题）。
chartResize.test.ts 以 layerchart 真渲染重写 4 个合同用例：jsdom 真实
SVG、width prop 跨视口变更、无重挂载的 in-place RO 收缩、零布局宿主
RO 回调不抛错。test-setup.ts 增加 window.matchMedia shim（layerchart
settings 上下文需要）并移除因此失效的 @ts-expect-error。

[影响范围]
回测结果/对比曲线等消费方在后续页面提交中切换到本 API；svelte-check
对 layerchart 复杂泛型以 as never 收口，0 error。

3 files changed, 180 insertions, 141 deletions

diff --git a/frontend/src/components/Chart.svelte b/frontend/src/components/Chart.svelte
index ca8f4f8..0854f3a 100644
--- a/frontend/src/components/Chart.svelte
+++ b/frontend/src/components/Chart.svelte
@@ -1,67 +1,77 @@
 <script lang="ts">
   import { onMount, onDestroy } from 'svelte';
-  import type * as echartsNS from 'echarts';
+  import { LineChart } from 'layerchart';
 
+  export interface ChartSeries {
+    key: string;
+    label?: string;
+    /** mutation-free accessor: long-format field name in the data rows */
+    value: string | ((row: never) => unknown) | undefined;
+    color?: string;
+    dashed?: boolean;
+    area?: boolean;
+    opacity?: number;
+  }
   interface Props {
-    option: echartsNS.EChartsOption;
+    // long-format rows: { i, date, [key]: value }
+    data: {
+      [key: string]: string | number | undefined;
+      i: number;
+    }[];
+    series: ChartSeries[];
     height?: number;
+    /** explicit width; when omitted the renderer measures its host (browser) */
+    width?: number;
     ariaLabel?: string;
+    legend?: boolean;
   }
-  let { option, height = 360, ariaLabel = '图表' }: Props = $props();
+  let { data, series, height = 340, width = $bindable(undefined), ariaLabel = '图表', legend = true }: Props = $props();
 
   let host: HTMLDivElement;
-  let chart: echartsNS.ECharts | null = null;
   let observer: ResizeObserver | null = null;
+  let measured: number | undefined = $state(undefined);
 
-  onMount(async () => {
-    // ECharts chunk loads lazily when a result/comparison view is opened.
-    const echarts = (await import('echarts')) as typeof echartsNS;
-    if (!host) return;
-    // Pass explicit sizes when the host has no layout yet (jsdom regression
-    // tests report 0×0 and ECharts warns "Can't get DOM width or height").
-    // In a real browser clientWidth/clientHeight are non-zero, so the measured
-    // size is used exactly as before; responsive resizing still works through
-    // the ResizeObserver below.
-    chart = echarts.init(host, undefined, {
-      renderer: 'svg',
-      width: host.clientWidth || 640,
-      height: host.clientHeight || height
-    });
-    observer = new ResizeObserver(() => {
-      if (!chart) return;
-      // re-measure on EVERY resize callback and pass the measured size
-      // explicitly: echarts keeps the width given at init/resize, so a
-      // desktop->mobile viewport change would otherwise leave the SVG at the
-      // old width and overflow the page (real, re-verified live bug).
-      const w = host.clientWidth || undefined;
-      const h = host.clientHeight || undefined;
-      if (w === undefined && h === undefined) return;
-      chart.resize({ width: w, height: h });
-    });
-    observer.observe(host);
-    chart?.setOption(option, { notMerge: true });
-  });
+  // Same resize semantics as the previous echarts wrapper (chartResize.test):
+  // re-measure the host on EVERY resize callback and push the measured size
+  // down; the svg must follow the host, never stick at a stale desktop width.
+  function applyMeasure() {
+    const w = host?.clientWidth;
+    if (w && w > 0) measured = w;
+  }
 
-  onDestroy(() => {
-    observer?.disconnect();
-    chart?.dispose();
-    chart = null;
+  onMount(() => {
+    applyMeasure();
+    if (typeof ResizeObserver !== 'undefined') {
+      observer = new ResizeObserver(applyMeasure);
+      observer.observe(host);
+    }
   });
+  onDestroy(() => observer?.disconnect());
 
-  $effect(() => {
-    chart?.setOption(option, { notMerge: true });
-  });
-</script>
+  const lcSeries = $derived(
+    series.map((s) => ({
+      key: s.key,
+      label: s.label ?? s.key,
+      value: s.value,
+      color: s.color
+    }))
+  );
 
-<div
-  bind:this={host}
-  style="height:{height}px; width:100%; min-width:0;"
-  role="img"
-  aria-label={ariaLabel}
-></div>
+  // Resize semantics (chartResize.test contract): a live host measurement
+  // always wins (the svg follows the real viewport), the width prop is the
+  // initial/testing size, 640 is the no-layout fallback.
+  const resolvedWidth = $derived(measured ?? width ?? 640);
+</script>
 
-<style>
-  div {
-    display: block;
-  }
-</style>
+<div bind:this={host} style="height:{height}px; width:100%; min-width:0;" role="img" aria-label={ariaLabel}>
+  <LineChart
+    data={data as never[]}
+    x="i"
+    series={lcSeries as never}
+    width={resolvedWidth}
+    {height}
+    {legend}
+    axis
+    clip
+  />
+</div>
diff --git a/frontend/src/lib/chartResize.test.ts b/frontend/src/lib/chartResize.test.ts
index 95beaad..2559120 100644
--- a/frontend/src/lib/chartResize.test.ts
+++ b/frontend/src/lib/chartResize.test.ts
@@ -1,131 +1,144 @@
 // @ts-nocheck
-import { describe, expect, it, beforeEach, vi } from 'vitest';
+import { describe, expect, it, beforeEach, afterEach, vi } from 'vitest';
 import { mount, unmount } from 'svelte';
 import Chart from '../components/Chart.svelte';
 
 // Bounded chart-overflow regression (parent live QA: viewport 375,
-// document.scrollWidth 1133 after desktop->mobile resize):
+// document.scrollWidth 1133 after desktop->mobile resize), reimplemented for
+// the layerchart/shadcn migration:
 //
-// echarts.init previously received an explicit width, and ECharts KEEPS the
-// explicitly passed size on chart.resize(); a desktop->mobile viewport change
-// therefore left the rendered SVG at the desktop width, overflowing the page.
-// The ResizeObserver handler must now re-measure the host and pass the
-// measured size into chart.resize() so the SVG actually shrinks with the
-// viewport. The chart output (SVG renderer) itself must stay fully real —
-// this test drives a genuine echarts SVG instance in jsdom (only zrender's
-// canvas measureText is shimmed) and asserts the SVG element's width follows
-// the host size on a simulated resize (fresh 375 deep links were already
-// correct; this covers the persistent resize path).
+// The old echarts wrapper kept an explicitly-passed width across resize()
+// calls, leaving the SVG stuck at desktop width after a viewport shrink.
+// The layerchart renderer owns its own container measurements now, and this
+// wrapper's contract is: the rendered SVG size must always follow the wrapper
+// width prop / host measurement — never stick at a stale "desktop" width.
+//
+// The chart output (SVG renderer) itself stays fully real — the test mounts
+// the genuine layerchart Chart in jsdom and asserts the SVG element's
+// rendered size follows the width prop (fresh render = the fresh-375 deep
+// link case; reactive render = the in-place viewport change case).
+
+const data = [
+  { i: 0, date: '2026-01-01', equity: 1.0 },
+  { i: 1, date: '2026-01-02', equity: 1.05 },
+  { i: 2, date: '2026-01-03', equity: 0.98 }
+];
+const series = [{ key: 'equity', label: '策略权益', color: '#0f766e', value: 'equity' }];
 
-interface CapturedRO {
-  callback: () => void;
-  el: Element;
+function svgSize(host: HTMLElement): number | null {
+  const svg = host.querySelector('svg');
+  if (!svg) return null;
+  const attrW = svg.getAttribute('width');
+  if (attrW) return parseFloat(attrW);
+  const style = svg.getAttribute('style') ?? '';
+  const m = /(?:^|;)\s*width:\s*(\d+(?:\.\d+)?)px/.exec(style);
+  if (m) return parseFloat(m[1]);
+  const vb = (svg.getAttribute('viewBox') || '').split(/[\s,]+/);
+  return vb.length >= 4 ? parseFloat(vb[2]) : null;
 }
-let captured: CapturedRO[] = [];
 
+let captured = [];
 function makeResizeObserverCtor() {
   return class FakeResizeObserver {
-    cb: () => void;
-    el: Element | null = null;
-    constructor(cb: ResizeObserverCallback) {
+    cb;
+    constructor(cb) {
       this.cb = cb;
-      captured.push({ callback: () => cb([], this as unknown as ResizeObserver), el: null as never });
+      captured.push(() => cb([], this));
     }
-    observe(el: Element) {
-      const capture = captured[captured.length - 1];
-      if (capture) capture.el = el;
+    observe(el) {
+      if (captured.length > 0) captured[captured.length - 1].el = el;
     }
     unobserve() {}
     disconnect() {}
   };
 }
 
-const baseOption = {
-  grid: { top: 24, left: 60, right: 24, bottom: 54 },
-  xAxis: { type: 'category', data: ['a', 'b'] },
-  yAxis: { type: 'value' },
-  series: [{ name: 'x', type: 'line' as const, data: [1, 2], showSymbol: false }]
-};
-
-function hostSvgWidth(host: HTMLElement): number | null {
-  const svg = host.querySelector('svg');
-  if (!svg) return null;
-  const attr = svg.getAttribute('width');
-  if (attr) return parseFloat(attr);
-  const style = svg.getAttribute('style') ?? '';
-  const m = /(?:^|;)\s*width:\s*(\d+(?:\.\d+)?)px/.exec(style);
-  return m ? parseFloat(m[1]) : null;
+async function mountChart(props) {
+  const host = document.createElement('div');
+  host.style.width = '900px';
+  document.body.appendChild(host);
+  const inst = mount(Chart, { target: host, props });
+  await new Promise((r) => setTimeout(r, 150));
+  return { host, inst };
 }
 
-describe('Chart resize follows host width (desktop→mobile overflow root cause)', () => {
+describe('Chart (layerchart) render + resize contract', () => {
   beforeEach(() => {
     captured = [];
     vi.stubGlobal('ResizeObserver', makeResizeObserverCtor());
   });
+  afterEach(() => vi.unstubAllGlobals());
 
-  it('init uses measured/fallback size, then resizes the SVG when the host shrinks', async () => {
+  it('layerchart SVG must be real in jsdom (fallback width 640 when host has no layout)', async () => {
     const host = document.createElement('div');
-    host.style.width = '900px';
     document.body.appendChild(host);
-    const originalW = Object.getOwnPropertyDescriptor(HTMLElement.prototype, 'clientWidth');
-    Object.defineProperty(host, 'clientWidth', { configurable: true, get() { return 900; } });
-    try {
-      const inst = mount(Chart, {
-        target: host,
-        props: { option: baseOption, height: 340, ariaLabel: '曲线' }
-      });
-      // let the lazy echarts import mount
-      await new Promise((r) => setTimeout(r, 120));
-      const ro = captured[captured.length - 1];
-      expect(ro).toBeTruthy();
-      expect(ro.el).toBe(host.firstElementChild); // observer watches the bind host
-      const inner = ro.el as HTMLElement;
+    const inst = mount(Chart, { target: host, props: { data, series, height: 340, ariaLabel: '曲线' } });
+    await new Promise((r) => setTimeout(r, 150));
+    const svg = host.querySelector('svg');
+    expect(svg, 'layerchart SVG renderer must be real in tests').toBeTruthy();
+    expect(svgSize(host), 'fallback width must be applied, not 0/degenerate').toBe(640);
+    unmount(inst);
+    host.remove();
+  });
 
-      const svg = inner.querySelector('svg');
-      expect(svg, 'echarts SVG renderer must be real in tests').toBeTruthy();
-      // initial size: measured/fallback (target has no clientWidth -> 640)
-      expect(parseFloat(svg!.getAttribute('width')!)).toBe(640);
+  it('svg width follows the wrapper width prop across a viewport change (900 → 340)', async () => {
+    const first = await mountChart({ data, series, height: 340, width: 900, ariaLabel: '曲线' });
+    expect(svgSize(first.host), 'desktop width must be rendered').toBe(900);
+    unmount(first.inst);
+    first.host.remove();
 
-      // seed the chart at a "desktop" width, then shrink the host (viewport
-      // resize) and fire the observer: svg must follow, not stay sticky
-      const setW = (v: number) => Object.defineProperty(inner, 'clientWidth', { configurable: true, get() { return v; } });
-      setW(900);
-      ro.callback();
-      await new Promise((r) => setTimeout(r, 40));
-      expect(parseFloat(inner.querySelector('svg')!.getAttribute('width')!)).toBe(900);
+    // the desktop->mobile in-place resize case: renderer must not stick to the
+    // previously rendered width
+    const second = await mountChart({ data, series, height: 340, width: 340, ariaLabel: '曲线' });
+    expect(svgSize(second.host), 'mobile width must be rendered, not the desktop width').toBe(340);
+    unmount(second.inst);
+    second.host.remove();
+  });
 
-      // now the actual overflow scenario: shrink to 375-device width
-      setW(340);
-      ro.callback();
-      await new Promise((r) => setTimeout(r, 40));
+  // In-place viewport change without remount: resize the host and fire the
+  // ResizeObserver callback. The wrapper must re-measure and push the new
+  // width down (the width prop is only the initial size — the live
+  // measurement always wins, matching the old echarts contract).
+  it('in-place host resize via ResizeObserver updates the svg without a remount', async () => {
+    const target = document.createElement('div');
+    target.style.width = '900px';
+    document.body.appendChild(target);
+    const inst = mount(Chart, {
+      target,
+      props: { data, series, height: 340, ariaLabel: '曲线' }
+    });
+    await new Promise((r) => setTimeout(r, 150));
 
-      const svgAfter = inner.querySelector('svg')!;
-      const wAfter = svgAfter!.getAttribute('width');
-      expect(wAfter, 'svg must shrink on resize, not keep desktop width').toBeTruthy();
-      expect(parseFloat(wAfter!)).toBe(340);
+    // emulate a measurable wrapper host (jsdom has no layout engine):
+    // the wrapper's internal role="img" div is the observed element
+    const inner = target.querySelector('div[role="img"]');
+    expect(inner).toBeTruthy();
+    let hostWidth = 900;
+    Object.defineProperty(inner, 'clientWidth', { get: () => hostWidth, configurable: true });
+    for (const fire of captured) fire();
+    await new Promise((r) => setTimeout(r, 120));
+    expect(svgSize(target), 'desktop width must be rendered first').toBe(900);
 
-      unmount(inst);
-      host.remove();
-      vi.unstubAllGlobals();
-    } finally {
-      Object.defineProperty(host, 'clientWidth', { configurable: true, get: () => 0 });
-    }
+    // viewport shrink in place: narrowed host + RO callback (no remount)
+    hostWidth = 280;
+    for (const fire of captured) fire();
+    await new Promise((r) => setTimeout(r, 120));
+    expect(svgSize(target), 'mobile width must be rendered, not the desktop width').toBe(280);
+    unmount(inst);
+    target.remove();
   });
 
-  it('does not pass undefined sizes to resize when host has no layout (avoid degenerate resize)', async () => {
+  it('zero-layout host: fake resize callbacks must not throw and svg stays alive', async () => {
     const host = document.createElement('div');
     document.body.appendChild(host);
-    const inst = mount(Chart, {
-      target: host,
-      props: { option: baseOption, height: 340, ariaLabel: '曲线' }
-    });
-    await new Promise((r) => setTimeout(r, 120));
-    const ro = captured[captured.length - 1];
-    expect(ro?.el).toBeTruthy();
-    // host with zero layout: callback must be a no-op (no degenerate 0-width resize)
-    expect(() => ro.callback()).not.toThrow();
+    const inst = mount(Chart, { target: host, props: { data, series, height: 340, ariaLabel: '曲线' } });
+    await new Promise((r) => setTimeout(r, 150));
+    expect(captured.length).toBeGreaterThan(0);
+    expect(() => {
+      for (const fire of captured) fire();
+    }).not.toThrow();
+    expect(host.querySelector('svg')).toBeTruthy();
     unmount(inst);
     host.remove();
-    vi.unstubAllGlobals();
   });
 });
diff --git a/frontend/src/test-setup.ts b/frontend/src/test-setup.ts
index cdd6071..10f9568 100644
--- a/frontend/src/test-setup.ts
+++ b/frontend/src/test-setup.ts
@@ -1,4 +1,20 @@
 
+// layerchart reads window.matchMedia (settings context, dark-mode aware
+// styling) in jsdom where no backend exists. Narrow shim for media queries
+// used by chart settings only.
+if (typeof window !== 'undefined' && !window.matchMedia) {
+  window.matchMedia = (query: string) => ({
+    matches: false,
+    media: query,
+    onchange: null,
+    addEventListener: () => {},
+    removeEventListener: () => {},
+    addListener: () => {},
+    removeListener: () => {},
+    dispatchEvent: () => false
+  });
+}
+
 // jsdom does not implement Range.getClientRects, which CodeMirror's
 // measurement layer calls for drawing decorations (diagnostics markers).
 // Without it the suite emits an unhandled