Add delete functionality to canvas card with confirmation dialog

- Implemented delete action for canvas cards, including a confirmation dialog.
- Updated `canvas-card.tsx` to support renaming and deleting canvases.
- Enhanced documentation in `CLAUDE.md` to reflect new features and mutations.
- Added success and error toast messages for delete actions.

lib/toast-messages.ts

@@ -188,5 +188,7 @@ export const msg = {
     renameEmpty: { title: "Name ungültig", desc: "Name darf nicht leer sein." },
     renameSuccess: { title: "Arbeitsbereich umbenannt" },
     renameFailed: { title: "Umbenennen fehlgeschlagen" },
+    deleteSuccess: { title: "Arbeitsbereich gelöscht" },
+    deleteFailed: { title: "Löschen fehlgeschlagen" },
   },
 } as const;