fix: restore controls after task completion

agent/agent.py

@@ -631,7 +631,8 @@ async def handle_job(ctx: JobContext) -> None:
             voice_enabled = mode == "voice"
             logger.info("Switching conversation mode to %s", mode)
             if not voice_enabled:
-                asyncio.create_task(session.interrupt())
+                # interrupt() returns an already-scheduled Future, not a coroutine.
+                session.interrupt()
             session.input.set_audio_enabled(voice_enabled)
             session.output.set_audio_enabled(voice_enabled)
             return