When the radio firmware is unresponsive but not yet flagged as zombie,
send_advert() would hang indefinitely on the main event loop, blocking
all packet processing (no data in/out) for 60+ seconds until the
scheduler thread's future.result() timed out — but that only timed
out the waiting thread, not the coroutine itself.
Fix: wrap every send_advert() call that runs on the event loop with
asyncio.wait_for(timeout=30.0). On timeout in the interval-advert
path, _radio_fail_count is incremented so repeated timeouts feed into
the existing zombie-detection threshold.
Stacy Olivas
22e1b2b53c