feat(system): process heartbeat + /system/health, engine runs business fields (W9-I)

- process_heartbeat / process_heartbeat_sample (0034): api / worker / worker:agent / all
  upsert every 15s (event loop lag last/max, concurrency, running runs, SSE connections, memory)
- GET /system/health (admin): processes with 45s stale flag, SSE, DB latency/size/connections,
  disks (DATA_DIR / library roots / download dirs, cache thresholds), mount sentinel checks
  with IO timeout, engine pending/oldest/24h failure rate, schedules
- GET /system/health/history?hours=: bucketed lag / running / SSE series
- /engine/runs and /engine/runs/{id}: business {kind, refId, title, triggeredBy} joined from
  run input / task / agent_run / tasks_run_meta / outbox; businessKind / businessRefId filters
- docs/runbook/ops.md: field meanings and alert thresholds

Co-Authored-By: Claude Opus 5.5 <[email protected]>

packages/contracts/src/api.ts

@@ -1654,6 +1654,21 @@ export const Api = {
       summary: "服务健康状态(免鉴权)",
       response: HealthStatus,
     }),
+    healthDetail: ep({
+      method: "get",
+      path: "/system/health",
+      scope: "admin",
+      summary: "进程与健康:进程心跳 / 事件循环延迟 / SSE 连接 / DB / 磁盘 / 挂载根 / 引擎 / 定时任务",
+      response: ops.SystemHealth,
+    }),
+    healthHistory: ep({
+      method: "get",
+      path: "/system/health/history",
+      scope: "admin",
+      summary: "心跳采样时间序列(事件循环延迟、运行中 run、SSE 连接;按桶聚合)",
+      query: ops.SystemHealthHistoryQuery,
+      response: ops.SystemHealthHistory,
+    }),
   },
 
   // ── 引擎面板(仅 admin) ──