Connect to tool output stream (WebSocket)

WebSocket endpoint for receiving streaming output from an object tool execution. The token is obtained from POST /v1/object-tools/{tool-id}/execute with stream=true. Token is single-use and expires after 30 seconds.

Server sends JSON text frames:

• {"type":"output","data":"..."} - output chunk
• {"type":"result","data":"..."} - script return value (server-script tools only)
• {"type":"completed"} - execution finished successfully
• {"type":"error","message":"..."} - execution failed