fix: Consider RPC channel health based on MQTT session

Use the MQTT session for the health rather than the "subscription". It is straight foward to add a topic when sending an RPC so we assume we can do that on demand when sending the RPC.

Author: allenporter

roborock/devices/v1_channel.py

@@ -199,7 +199,7 @@ def is_local_connected(self) -> bool:
     @property
     def is_mqtt_connected(self) -> bool:
         """Return whether MQTT connection is available."""
-        return self._mqtt_unsub is not None and self._mqtt_channel.is_connected
+        return self._mqtt_channel.is_connected
 
     @property
     def rpc_channel(self) -> V1RpcChannel:

tests/devices/test_v1_channel.py

@@ -256,7 +256,7 @@ async def test_v1_channel_subscribe_local_success(
     assert mock_local_channel.subscribers
 
     # Verify properties
-    assert not v1_channel.is_mqtt_connected
+    assert v1_channel.is_mqtt_connected
     assert v1_channel.is_local_connected
 
     # Test unsubscribe cleans up both