fix: address ObsidianReviewBot code review issues

- Fix template literal type issue in notifications.ts by adding
  explicit String() coercion for args.recursive
- Replace Vault.trash() with FileManager.trashFile() to respect
  user's configured deletion preferences (system trash or .trash/)
- Remove unused trash() method from IVaultAdapter and VaultAdapter
- Update tests to reflect new deletion behavior

src/ui/notifications.ts

@@ -163,7 +163,7 @@ export class NotificationManager {
 				keyParams.push(`folder: "${this.truncateString(args.folder, 30)}"`);
 			}
 			if (args.recursive !== undefined) {
-				keyParams.push(`recursive: ${args.recursive}`);
+				keyParams.push(`recursive: ${String(args.recursive)}`);
 			}
 
 			// If no key params, show first 50 chars of JSON