feat: add shared API utilities for handling requests and responses

- Introduced `shared.ts` with utility functions for API interactions, including JSON parsing, error handling, and content disposition parsing.
- Added `vault.ts` to manage vault-related operations such as folder and cipher management, including creation, deletion, and bulk operations.
- Implemented encryption and decryption methods for secure data handling within the vault.
- Created `backup-settings-repair.ts` to automatically repair backup settings for admin profiles if needed.

src/handlers/backup.ts

@@ -75,9 +75,6 @@ async function executeConfiguredBackup(
 ): Promise<{ fileName: string; fileSize: number; remotePath: string; provider: string }> {
   const currentSettings = await loadBackupSettings(storage, env, 'UTC');
   const destination = requireBackupDestination(currentSettings, destinationId);
-  if (destination.type === 'placeholder') {
-    throw new Error('The reserved backup destination is not available yet');
-  }
 
   const now = new Date();
   destination.runtime.lastAttemptAt = now.toISOString();