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/environment/environment.service.ts

@@ -384,6 +384,21 @@ export class EnvironmentService {
     return Number.isFinite(parsed) && parsed > 0 ? parsed : 15000;
   }
 
+  /**
+   * Spawned `git http-backend` watchdog timeout in ms (default 120000). Bounds a
+   * single smart-HTTP request so a stalled `git-receive-pack` cannot hold the
+   * per-space lock forever (the child is killed and a 500 sent on expiry). A NaN /
+   * non-positive value falls back to the default so a bad override can never
+   * disable the watchdog.
+   */
+  getGitSyncBackendTimeoutMs(): number {
+    const v = parseInt(
+      this.configService.get<string>('GIT_SYNC_BACKEND_TIMEOUT_MS', '120000'),
+      10,
+    );
+    return Number.isFinite(v) && v > 0 ? v : 120000;
+  }
+
   /**
    * Event debounce window in ms (default 2000). A NaN / non-positive value falls
    * back to the default so a bad override can never disable the debounce.