Add real-time synchronization for collection book removal:
- Extract user ID from context for targeted broadcasts
- Broadcast 'collection_updated' message to user's other devices
- Includes collection_id, action, and book_id in message payload
This ensures that when a user removes a book from a collection,
all their connected devices (browser tabs, mobile apps, etc.)
receive real-time updates via WebSocket.
Consistent with existing AddBooks and BulkRemoveBooks operations
which already use BroadcastToUser for synchronization.
john-okeefe
cb46cd310f