Fix client disconnection handling in cluster master

- Made assign_job_to_worker, _transfer_job_files, _transfer_file_via_websocket, enable_process, disable_process, update_process_weight, restart_client_workers, and restart_client_worker async methods
- Added proper exception handling for websocket send operations
- When websocket send fails due to broken connection, clients are now properly removed from available workers selection
- This ensures that disconnected clients are immediately removed from the worker pool and jobs are re-assigned to available workers