test(git-sync): add reviewer-requested coverage across engine, server, client

Implements the test cases called out in the PR #119 review threads
(code-review, test-strategy report, red-team) — TESTS ONLY, no production
code changes.

packages/git-sync (vitest):
- lib converter/markdown gaps: pageBreak data-loss (it.fails repro),
  subpages lossy round-trip, nested/fenced callouts, ol->taskList bridge,
  column.width number<->string drift, empty details.
- engine units: parentFolderFile, planReconciliation swap/chained move,
  buildVaultLayout last-resort-by-id, firstDivergence, applyPushActions /
  applyPullActions failure isolation.
- real temp-git integration: diffNameStatus -z rename+add/modify
  alignment, copy-line behavior, per-invocation committer identity (no
  leak into repo/global config).
- ENFORCED type-level GitSyncClient contract via vitest typecheck over a
  *.test-d.ts file (tsconfig.vitest.json; build tsconfig untouched).

apps/server (jest):
- orchestrator: delete-cap neutralization + fail-safe, Redis lock / mutex
  skip ladder + release-on-throw, merge guard, pull/push order, remote
  template substitution, poll lifecycle.
- page-change listener: loop-guard, debounce coalescing, id resolution,
  error swallowing.
- vault registry, controller authz (trigger + status), env
  validation/getters, page.service git-sync provenance stamping,
  persistence precedence (agent > git-sync > user) + no boundary snapshot,
  space.service audit-delta, space.repo jsonb-merge, converter-gate corpus
  extension (mention/math/details/marks).

apps/client (vitest + testing-library):
- history-item git-sync badge: render gating + non-clickable.
- edit-space-form toggle: initial state, optimistic payload, rollback on
  error, disabled states.

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

packages/git-sync/tsconfig.vitest.json

@@ -0,0 +1,15 @@
+{
+  // Test-infra tsconfig used ONLY by vitest's `test.typecheck` pass (Finding #1).
+  // The build tsconfig (`tsconfig.json`) scopes the compiler to `src/**` with
+  // `rootDir: ./src`, so it never type-checks the `test/` tree. This config
+  // inherits the same strict compiler options but widens the file set to the
+  // type-test files so `vitest run` can run `tsc` over them. It is NOT used by
+  // `npm run build` (that still uses `tsconfig.json`), so it has no effect on the
+  // shipped output.
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "noEmit": true,
+    "rootDir": "."
+  },
+  "include": ["test/**/*.test-d.ts", "src/**/*"]
+}