fix(worktree): address PR review — test assertion, dry-run sentinel, git timeouts

- Update allProjects test expectation to match [parent, composite] (matches JSDoc + callers in ContextBuilder/context handlers).
- Replace string-matched __DRY_RUN_ROLLBACK__ sentinel with dedicated DryRunRollback class to avoid swallowing unrelated errors.
- Add 5000ms timeout to spawnSync git calls in WorktreeAdoption and ProcessManager so worker startup can't hang on a stuck git process.
- Drop unreachable break after process.exit(0) in adopt case.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/services/infrastructure/ProcessManager.ts

@@ -685,7 +685,10 @@ type CwdClassification =
   | { kind: 'skip' };
 
 function gitQuery(cwd: string, args: string[]): string | null {
-  const r = spawnSync('git', ['-C', cwd, ...args], { encoding: 'utf8' });
+  const r = spawnSync('git', ['-C', cwd, ...args], {
+    encoding: 'utf8',
+    timeout: 5000
+  });
   if (r.status !== 0) return null;
   return (r.stdout ?? '').trim();
 }