uvc: ack SET_CUR after data

server/src/bin/lesavka-uvc.rs

@@ -525,7 +525,8 @@ fn handle_data(
                 );
             }
         }
-        // No extra response required; ep0 data stage completion ends the control transfer.
+        // ACK the OUT transfer after we've processed the payload.
+        let _ = send_response(fd, uvc_send_response, &[]);
     }
 }