feat: implement NotificationsHub for real-time vault sync notifications

- Added NotificationsHub durable object to handle WebSocket connections for vault sync notifications.
- Integrated SignalR protocol for message framing and communication.
- Updated storage service methods to return revision date and user ID for vault sync notifications.
- Enhanced existing handlers (attachments, ciphers, folders, sends, and import) to notify users of vault sync events.
- Created new notifications handler for WebSocket negotiation and binding user IDs.
- Updated frontend to establish WebSocket connection for receiving vault sync notifications.
- Improved CORS headers to support new notification endpoints.
- Bumped wrangler version in package.json to 4.71.0.

src/utils/device.ts

@@ -72,3 +72,7 @@ export function readKnownDeviceProbe(request: Request): { email: string | null;
   return { email, deviceIdentifier };
 }
 
+export function readActingDeviceIdentifier(request: Request): string | null {
+  return normalizeDeviceIdentifier(request.headers.get('X-NodeWarden-Acting-Device-Id'));
+}
+