Fix method call in cluster master register processes

- Use _get_client_by_websocket instead of non-existent _get_client_by_socket
- Fixes client connection error during process registration

vidai/cluster_master.py

@@ -227,7 +227,7 @@ class ClusterMaster:
 
     def _handle_register_processes(self, message: Dict[str, Any], websocket: websockets.WebSocketServerProtocol) -> Dict[str, Any]:
         """Handle process registration from client."""
-        client_id = self._get_client_by_socket(client_sock)
+        client_id = self._get_client_by_websocket(websocket)
         if not client_id:
             return {'type': 'error', 'message': 'Client not authenticated'}