Add desktop-backed confirm dialog API for worktree deletion

- add `dialogs.confirm` to native IPC/contracts and desktop preload/main bridge
- switch sidebar worktree deletion prompt from `window.confirm` to native API
- add `showDesktopConfirmDialog` helper with unit tests for dialog behavior
0068a93cfaJulius Marminge committed on 2/13/2026, 6:57:56 AM· committed by Julius Marmingeparentdd91266
8 files changedLine totals unavailable