feat(frontend): 首页指标卡与项目行 sparkline（前端重设计第二轮之一）

[变更性质] 新增能力，不动后端。
[新增功能] dashboardMetrics 聚合（项目/数据集/实验/AI 用量统计 + 最近回测首末净值），实盘数据优先、缺数以占位符 '-' 兜底；ProjectMetricRow 渲染 4 张 metric-card；Sparkline 组件输出 up/down 方向线段与端点圆点。
[实现方案] 聚合逻辑与展示组件分离，sparkline 仅依赖 first/last 两个字段，无图表库依赖。
[影响范围] frontend/src/lib 与 components；配套 5 组单测（dashboardMetrics/sparkline/metricRow）。

1 files changed, 79 insertions, 0 deletions

diff --git a/frontend/src/lib/dashboardMetrics.ts b/frontend/src/lib/dashboardMetrics.ts
new file mode 100644
index 0000000..2801c9d
--- /dev/null
+++ b/frontend/src/lib/dashboardMetrics.ts
@@ -0,0 +1,79 @@
+// Leader round2 spec: 登录后默认页顶部指标卡 + 项目行迷你权益缩略图。
+// 纯函数层，聚合合同在 dashboardMetrics.test.ts 做真实断言。
+// 取不到的字段一律占位 "-"，不得编造数字。
+
+export interface DashboardMetric {
+  projectCount: number;
+  datasetCount: number;
+  runningRuns: number;
+  doneRuns: number;
+  /** "7 次" 或 "-"（后端无请求计数时） */
+  usageLabel: string;
+  /** 次要说明：token 计数摘要，无数据为空串 */
+  usageTokens: string;
+}
+
+function kify(n: number): string {
+  if (n >= 10000) return `${Math.round(n / 1000)}k`;
+  if (n >= 1000) return `${(n / 1000).toFixed(1)}k`;
+  return `${n}`;
+}
+
+export function aggregateDashboard(input: {
+  projects?: { id: string }[] | null;
+  datasets?: { id: string }[] | null;
+  runs?: { id: string; status: string; result?: unknown }[] | null;
+  usage?: { totals?: { input_tokens?: number; output_tokens?: number; requests?: number } } | null;
+}): DashboardMetric {
+  const projects = Array.isArray(input.projects) ? input.projects : [];
+  const datasets = Array.isArray(input.datasets) ? input.datasets : [];
+  const runs = Array.isArray(input.runs) ? input.runs : [];
+  const runningRuns = runs.filter((r) => r.status === 'running' || r.status === 'queued').length;
+  const doneRuns = runs.filter((r) => r.status === 'succeeded').length;
+
+  const t = input.usage?.totals;
+  let usageLabel = '-';
+  let usageTokens = '';
+  if (t && typeof t.requests === 'number') {
+    usageLabel = `${t.requests} 次`;
+    const inTok = t.input_tokens ?? 0;
+    const outTok = t.output_tokens ?? 0;
+    usageTokens = `(${kify(inTok)}/${kify(outTok)} tok)`;
+  }
+
+  return {
+    projectCount: projects.length,
+    datasetCount: datasets.length,
+    runningRuns,
+    doneRuns,
+    usageLabel,
+    usageTokens
+  };
+}
+
+export interface SparkEndpoints {
+  first: number;
+  last: number;
+}
+
+/**
+ * Per-project latest backtest endpoints for the project-row sparkline.
+ * Latest = max created_at among runs whose result carries equity points.
+ * A project without any chart-carrying run gets NO entry (caller must not
+ * render a sparkline in that case).
+ */
+export function sparkFirstLast(
+  runs: { project_id?: string; created_at?: string; result?: { equity?: { equity: number }[] } | null }[]
+): Map<string, { first: number; last: number }> {
+  const best = new Map<string, { at: string; first: number; last: number }>();
+  const out = new Map<string, { first: number; last: number }>();
+  for (const r of runs) {
+    const eq = r.result?.equity;
+    if (!r.project_id || !Array.isArray(eq) || eq.length < 2) continue;
+    const prev = best.get(r.project_id);
+    if (prev && prev.at >= (r.created_at ?? '')) continue;
+    best.set(r.project_id, { at: r.created_at ?? '', first: eq[0].equity, last: eq[eq.length - 1].equity });
+  }
+  for (const [k, v] of best) out.set(k, { first: v.first, last: v.last });
+  return out;
+}