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.

wrangler.kv.toml

@@ -14,5 +14,13 @@ command = "npm run build"
 binding = "DB"
 database_name = "nodewarden-db"
 
+[[durable_objects.bindings]]
+name = "NOTIFICATIONS_HUB"
+class_name = "NotificationsHub"
+
 [[kv_namespaces]]
 binding = "ATTACHMENTS_KV"
+
+[[migrations]]
+tag = "v1-notifications-hub"
+new_sqlite_classes = ["NotificationsHub"]