fix(git-sync): address PR #119 review (#1571)

Resolve the code-review findings from comment #1571 on PR #119.

Engine (packages/git-sync):
- Idempotent CREATE on retry: before createPage, look the page up in the
  live Docmost tree by (parentPageId, title) and ADOPT it instead of
  duplicating when a prior cycle created it but failed to persist the
  pageId back to disk. Only trust a COMPLETE tree for the lookup; fall
  back to createPage otherwise. Covered by new tests incl. a complete=false
  regression-lock.
- Route applyPullActions diagnostics through an injected logger instead of
  bare console (thread log from the cycle).
- Add a timeout to the git execFile chokepoint (runRaw) so a hung git
  subprocess cannot wedge a sync cycle.
- Translate remaining Russian code comments to English.
- Remove dead standalone-CLI code (parseArgs/PushParsedArgs,
  parseSettings/envSchema, loadSettingsOrExit + config-errors.ts) and the
  matching index exports/specs; keep the Settings type.
- Fix the dangling docs link in package.json.
- Add a schema-surface snapshot guard so any drift in the vendored
  document schema is a loud, must-review CI failure (+ provenance header).

Server (apps/server):
- Add a configurable watchdog timeout to the spawned git http-backend so a
  stalled push cannot hold the per-space lock forever
  (GIT_SYNC_BACKEND_TIMEOUT_MS).
- Close the in-process TOCTOU window in SpaceLockService.withSpaceLock by
  reserving the slot synchronously before acquire.
- Add tests: removePage git-sync provenance (both branches), ensureServable
  force-push-protection git configs, and the phase-B+ datasource methods.

Docs / build:
- AGENTS.md: list git-sync as the fifth workspace package and note the
  three schema mirrors; fix the dangling git-sync-plan.md backlog link.
- pnpm-lock.yaml: add the missing @docmost/git-sync workspace link so
  pnpm install --frozen-lockfile (CI default) succeeds.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/server/src/integrations/git-sync/services/space-lock.service.ts

@@ -111,25 +111,33 @@ export class SpaceLockService {
     if (this.running.has(spaceId)) {
       return { skipped: 'in-progress' };
     }
-    if (!(await this.acquire(spaceId))) {
-      return { skipped: 'lock-held' };
-    }
+    // Reserve the in-process slot synchronously (before any await) so two
+    // concurrent same-space calls on THIS instance cannot both pass the guard and
+    // race acquire(). Redis NX is already authoritative across replicas; this just
+    // closes the in-process TOCTOU window. Released in the outer finally on every
+    // path (acquire-failure, fn-throw, normal completion).
     this.running.add(spaceId);
-    // Heartbeat: periodically (≈ TTL/3) extend the lock's TTL while `fn` runs so
-    // a long push (client-controlled receive-pack + the Docmost cycle) cannot
-    // outlive the fixed TTL and let a concurrent cycle race the working tree. The
-    // refresh is CAS-guarded (only extends while WE own it). `.unref()` keeps the
-    // timer from holding the event loop open; it is ALWAYS cleared in `finally`.
-    const heartbeat = setInterval(() => {
-      void this.refreshLock(spaceId);
-    }, Math.max(1, Math.floor(GIT_SYNC_LOCK_TTL_MS / 3)));
-    heartbeat.unref?.();
     try {
-      return await fn();
+      if (!(await this.acquire(spaceId))) {
+        return { skipped: 'lock-held' };
+      }
+      // Heartbeat: periodically (≈ TTL/3) extend the lock's TTL while `fn` runs so
+      // a long push (client-controlled receive-pack + the Docmost cycle) cannot
+      // outlive the fixed TTL and let a concurrent cycle race the working tree. The
+      // refresh is CAS-guarded (only extends while WE own it). `.unref()` keeps the
+      // timer from holding the event loop open; it is ALWAYS cleared in `finally`.
+      const heartbeat = setInterval(() => {
+        void this.refreshLock(spaceId);
+      }, Math.max(1, Math.floor(GIT_SYNC_LOCK_TTL_MS / 3)));
+      heartbeat.unref?.();
+      try {
+        return await fn();
+      } finally {
+        clearInterval(heartbeat);
+        await this.release(spaceId);
+      }
     } finally {
-      clearInterval(heartbeat);
       this.running.delete(spaceId);
-      await this.release(spaceId);
     }
   }
 }