gateway: handle websocket.disconnect in receive loop

Stops the RuntimeError spam ('Cannot call receive once a disconnect
message has been received') every time the device's watchdog reboots.
Redeployed to the tatlock-ui stack.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

gateway/src/desklock_gateway/main.py

@@ -54,6 +54,8 @@ async def voice(ws: WebSocket) -> None:
     try:
         while True:
             message = await ws.receive()
+            if message["type"] == "websocket.disconnect":
+                raise WebSocketDisconnect(message.get("code", 1000))
             device["last_seen"] = _now()
             if "bytes" in message and message["bytes"] is not None:
                 if recording: