Surface worktree removal failures after thread deletion

- wrap `git worktree remove` errors with command and cwd context
- add server test covering failed worktree removal messaging
- show an error toast and log details when orphaned worktree cleanup fails
077de88885Julius Marminge committed on 2/19/2026, 6:07:38 AMparentbb9371d
3 files changedLine totals unavailable