fix: Connect to D-Bus system bus explicitly

Co-authored-by: aider (gemini/gemini-2.5-pro) <aider@aider.chat>

main.py

@@ -12,6 +12,7 @@ import asyncio
 from aiomqtt import Client
 from dbus_next.aio import MessageBus
 from dbus_next.service import ServiceInterface, method
+from dbus_next.constants import BusType
 from dbus_next import Variant
 
 
@@ -183,7 +184,7 @@ async def fetch_mqtt():
 
 async def main():
     global bus
-    bus = await MessageBus().connect()
+    bus = await MessageBus(bus_type=BusType.SYSTEM).connect()
 
     logging.info('')
     logging.info('==========================')