* feat(files): add shift+click quick delete to File Manager
Add shift+click functionality to FilesModal for rapid file deletion without confirmation dialogs.
Changes:
- Track Shift key state via keyboard event listeners
- When Shift is held, delete button bypasses confirmation and deletes immediately
- Visual feedback: delete icon turns red when Shift is held
- Optimized delete to remove file from local array instead of re-fetching entire list, enabling rapid successive deletions without UI flicker
This matches the quick delete pattern used in other workspace components like Tools, Prompts, and Models.
* Update FilesModal.svelte
