chore(frontend): shadcn-svelte / Tailwind / layerchart 工具链初始化

[变更性质]
本轮为维护性依赖与配置初始化，不改变业务页面（页面迁移见后续提交）。

[维护内容]
按 Leader 返工指令，前端 UI 组件库全量迁移 shadcn-svelte，图表渲染
从 echarts 换为 layerchart，需要一次性引入配套依赖与构建配置。

[实现方案]
package.json/pnpm-lock.yaml：tailwindcss@4、@tailwindcss/vite、
tw-animate-css、shadcn-svelte、bits-ui、tailwind-variants、clsx、
tailwind-merge、@lucide/svelte、layerchart、@fontsource-variable/inter
与 @types/node；echarts 保留至页面迁移完成后移除。pnpm-workspace.yaml
声明 allowBuilds（esbuild、@tailwindcss/oxide）。components.json 采用
mira preset，别名 $lib。tsconfig 新增 $lib paths；vite.config.ts 加入
tailwindcss 插件、$lib alias（vitest 需要）与 test 环境配置。
src/lib/components/ 为 shadcn 生成的 UI 组件源码（button/input/label/
card/badge/alert/select/table/tabs/separator/chart），src/lib/utils.ts
为 cn 工具。app.css 引入 tailwind 与 shadcn CSS 变量并调整为 teal
主题（primary #0f766e、radius 0.375rem、双主题 chart-1..5），保留
legacy 选择器（banner/beat/table.data/metric 等），mobileCss.test.ts
依赖其语义断言。

[影响范围]
构建链与主题变量；后续页面提交逐步消费这些组件，npm run check/test/
build 已全绿验证。

1 files changed, 82 insertions, 0 deletions

diff --git a/frontend/src/lib/components/ui/button/button.svelte b/frontend/src/lib/components/ui/button/button.svelte
new file mode 100644
index 0000000..7669a5e
--- /dev/null
+++ b/frontend/src/lib/components/ui/button/button.svelte
@@ -0,0 +1,82 @@
+<script lang="ts" module>
+	import { type VariantProps, tv } from "tailwind-variants";
+	import { cn, type WithElementRef } from "$lib/utils.js";
+	import type { HTMLAnchorAttributes, HTMLButtonAttributes } from "svelte/elements";
+
+	export const buttonVariants = tv({
+		base: "focus-visible:border-ring focus-visible:ring-ring/30 aria-invalid:ring-destructive/20 dark:aria-invalid:ring-destructive/40 aria-invalid:border-destructive dark:aria-invalid:border-destructive/50 rounded-md border border-transparent bg-clip-padding text-xs/relaxed font-medium focus-visible:ring-2 aria-invalid:ring-2 active:not-aria-[haspopup]:translate-y-px [&_svg:not([class*='size-'])]:size-4 group/button inline-flex shrink-0 items-center justify-center whitespace-nowrap transition-all outline-none select-none disabled:pointer-events-none disabled:opacity-50 [&_svg]:pointer-events-none [&_svg]:shrink-0",
+		variants: {
+			variant: {
+				default: "bg-primary text-primary-foreground hover:bg-primary/80",
+				outline: "border-border dark:bg-input/30 hover:bg-input/50 hover:text-foreground aria-expanded:bg-muted aria-expanded:text-foreground",
+				secondary: "bg-secondary text-secondary-foreground hover:bg-[color-mix(in_oklch,var(--secondary),var(--foreground)_5%)] aria-expanded:bg-secondary aria-expanded:text-secondary-foreground",
+				ghost: "hover:bg-muted hover:text-foreground dark:hover:bg-muted/50 aria-expanded:bg-muted aria-expanded:text-foreground",
+				destructive: "bg-destructive/10 hover:bg-destructive/20 focus-visible:ring-destructive/20 dark:focus-visible:ring-destructive/40 dark:bg-destructive/20 text-destructive focus-visible:border-destructive/40 dark:hover:bg-destructive/30",
+				link: "text-primary underline-offset-4 hover:underline",
+			},
+			size: {
+				default: "h-7 gap-1 px-2 text-xs/relaxed has-data-[icon=inline-end]:pr-1.5 has-data-[icon=inline-start]:pl-1.5 [&_svg:not([class*='size-'])]:size-3.5",
+				xs: "h-5 gap-1 rounded-sm px-2 text-[0.625rem] has-data-[icon=inline-end]:pr-1.5 has-data-[icon=inline-start]:pl-1.5 [&_svg:not([class*='size-'])]:size-2.5",
+				sm: "h-6 gap-1 px-2 text-xs/relaxed has-data-[icon=inline-end]:pr-1.5 has-data-[icon=inline-start]:pl-1.5 [&_svg:not([class*='size-'])]:size-3",
+				lg: "h-8 gap-1 px-2.5 text-xs/relaxed has-data-[icon=inline-end]:pr-2 has-data-[icon=inline-start]:pl-2 [&_svg:not([class*='size-'])]:size-4",
+				icon: "size-7 [&_svg:not([class*='size-'])]:size-3.5",
+				"icon-xs": "size-5 rounded-sm [&_svg:not([class*='size-'])]:size-2.5",
+				"icon-sm": "size-6 [&_svg:not([class*='size-'])]:size-3",
+				"icon-lg": "size-8 [&_svg:not([class*='size-'])]:size-4",
+			},
+		},
+		defaultVariants: {
+			variant: "default",
+			size: "default",
+		},
+	});
+
+	export type ButtonVariant = VariantProps<typeof buttonVariants>["variant"];
+	export type ButtonSize = VariantProps<typeof buttonVariants>["size"];
+
+	export type ButtonProps = WithElementRef<HTMLButtonAttributes> &
+		WithElementRef<HTMLAnchorAttributes> & {
+			variant?: ButtonVariant;
+			size?: ButtonSize;
+		};
+</script>
+
+<script lang="ts">
+	let {
+		class: className,
+		variant = "default",
+		size = "default",
+		ref = $bindable(null),
+		href = undefined,
+		type = "button",
+		disabled,
+		children,
+		...restProps
+	}: ButtonProps = $props();
+</script>
+
+{#if href}
+	<a
+		bind:this={ref}
+		data-slot="button"
+		class={cn(buttonVariants({ variant, size }), className)}
+		href={disabled ? undefined : href}
+		aria-disabled={disabled}
+		role={disabled ? "link" : undefined}
+		tabindex={disabled ? -1 : undefined}
+		{...restProps}
+	>
+		{@render children?.()}
+	</a>
+{:else}
+	<button
+		bind:this={ref}
+		data-slot="button"
+		class={cn(buttonVariants({ variant, size }), className)}
+		{type}
+		{disabled}
+		{...restProps}
+	>
+		{@render children?.()}
+	</button>
+{/if}