fix(mqtt): force event topic resubscribe on reconnect [consent: user-approved]

src/simclient.py

@@ -919,8 +919,12 @@ def main():
             logging.info(f"Subscribed to: {group_id_topic}")
             
             # Wenn beim Start eine group_id vorhanden ist, sofort Event-Topic abonnieren
+            # Reset event_topic so subscribe_event_topic always re-registers with the broker
+            # (broker loses all subscriptions on reconnect, even if our local state still has it)
             if current_group_id:
                 logging.info(f"Subscribing to event topic for saved group_id: {current_group_id}")
+                nonlocal event_topic
+                event_topic = None  # force re-subscribe regardless of previous state
                 subscribe_event_topic(current_group_id)
             
             # Send discovery message after reconnection to re-register with server