feat(sources): site center backend (credentials, refresh login, user data, health check, delete)

PUT /sites/{id}/credentials by kind (moved from auth-settings, legacy body
accepted), POST refresh-login (async task or wait), POST health-check,
GET user-data history, DELETE /sites/{id} (soft delete, releases kept),
DELETE /site-accounts/{id}, GET /sites?include=accounts; refreshSiteAccount
task with login-failure decisions and auto re-login on auth_expired;
scheduled jobs sites.user_data (6h) and sites.health_check (1h);
settings.sites defaults for rate limit, snapshot interval, UA and proxy.

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

apps/server/test/sources-identity/mteam-tasks.test.ts

@@ -69,12 +69,13 @@ describe.skipIf(!up)("M-Team 快照与任务注册", () => {
     api.setFailMode(null);
   });
 
-  it("模块注册 4 个任务与 3 条 outbox 路由;任务处理器经 step.run 调服务", async () => {
+  it("模块注册 6 个任务与 3 条 outbox 路由;任务处理器经 step.run 调服务", async () => {
     const reg = new TaskRegistry();
     h.module.registerTasks(reg, h.ctx);
     expect(reg.names()).toEqual([
       "ingestFeed",
       "refreshMetadata",
+      "refreshSiteAccount",
       "resolveObservation",
       "searchSubscription",
       "snapshotSite",