feat(server): unified scheduled-job registry and scheduler; module timers moved onto it

- modules/schedules: registerScheduledJob({key, defaults, run}) registry; defaults are
  synced into scheduled_job without overriding user-changed enabled/schedule
- scheduler runs only on the io worker, one instance via pg_try_advisory_lock held on a
  dedicated connection; due = enabled and next_run_at reached, or run requested;
  jobs run in parallel, never re-entrant; interval next = finish + period, cron next match;
  run-now does not move next_run_at and merges duplicate requests; skip advances one period;
  history trimmed to the last 50 runs; interrupted runs marked failed on takeover
- agent_check jobs: trigger condition checked first, goal template rendered, runAgent
  enqueued via startRun(trigger=schedule) with allowlist and budget, one run per time slot;
  allowRecover uses the autoInvestigate grant check; results harvested back into the run
  history and optionally reported as an info decision; 3 built-in checks, off by default
- sources-identity (feeds.poll, sites.snapshot, identity.review), acquisition-organize
  (downloads.sync, cache.threshold, downloads.orchestrate, slots.reevaluate,
  subscriptions.search, subscriptions.metadata, library.reconcile) and file-manager
  (trash.purge) register jobs instead of running their own setInterval; default
  intervals unchanged; backup registered as an unconfigured placeholder
- endpoints under /schedules (admin, console session only)

TODO: pi refreshPiTokens and auth-settings session cleanup still own their timers.

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

apps/server/test/modules.test.ts

@@ -43,7 +43,7 @@ const pingModule: ServerModule = {
 };
 
 describe("ServerModule 骨架", () => {
-  it("清单里是四个 W2 模块 + 文件管理 + Pi 上游,名字唯一", () => {
+  it("清单里是四个 W2 模块 + 文件管理 + Pi 上游 + 定时任务(末尾),名字唯一", () => {
     expect(SERVER_MODULES.map((m) => m.name)).toEqual([
       "auth-settings",
       "sources-identity",
@@ -51,6 +51,7 @@ describe("ServerModule 骨架", () => {
       "agent",
       "file-manager",
       "pi",
+      "schedules",
     ]);
   });