fix(git): stop git process overflow

[jonathanlab]

lets batch incoming untracked changes instead of spawning a new git process for each one

[greptile-apps]

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 1
apps/code/src/renderer/hooks/useFileWatcher.ts:36-43
The timer cleanup effect has an empty dependency array, so it only runs on unmount. If `repoPath` changes while a 500 ms timer is pending, the old-path timer is not cancelled and will fire ~500 ms later calling `invalidateGitWorkingTreeQueries` with the stale path. Because there are no active query observers for that old path, TanStack Query won't refetch, so no git process is spawned — but adding `repoPath` to the deps array gives cleaner semantics and avoids the unnecessary invalidation entirely.

```suggestion
  useEffect(() => {
    return () => {
      if (gitInvalidateTimerRef.current) {
        clearTimeout(gitInvalidateTimerRef.current);
        gitInvalidateTimerRef.current = null;
      }
    };
  }, [repoPath]);
```

_{Reviews (1): Last reviewed commit: "fix(git): cancel superseded git status q..." | Re-trigger Greptile}