merge: maestro/tsk_lDx6zd-EbA00 [指标统计：执行时长 / 成功率 / 额度消耗估算]

# Conflicts:
#	web/style.css

src/api/server.ts

@@ -155,6 +155,13 @@ export function buildServer(opts: ApiOptions): FastifyInstance {
     return store.nextExecutable(id) ?? { next: null };
   });
 
+  // ---------- Metrics（健康度 + 成本聚合）----------
+  // GET /api/metrics?project=<id>；不带 project = 全部项目聚合。
+  app.get('/api/metrics', (req) => {
+    const q = req.query as { project?: string };
+    return store.metrics(q.project && q.project.trim() ? q.project.trim() : undefined);
+  });
+
   // ---------- Tasks ----------
   app.post('/api/projects/:id/tasks', (req) => {
     const { id } = req.params as { id: string };