fix: close Audio Router self-echo PUBACK/subscription-delivery race

publish_router_mode registered its self-echo correlation marker before
publishing but removed it in a finally block the instant the QoS 1 publish()
call observed its PUBACK. A broker may legally deliver a Controller's own
subscription copy of that same publish after the PUBACK, since MQTT does not
order the two; when that happened, the Controller mistook its own late echo
for live operator intent and relinquished automatic restoration ownership.

Keep the marker claimable for a short, bounded mqtt.router_echo_grace_seconds
window (default 2s) after the PUBACK instead of clearing it immediately.
Genuine external/operator commands are unaffected: once the grace window
elapses, a matching payload is still correctly treated as operator intent
and ownership is relinquished as before.

Verified with deterministic fake-clock unit tests plus a real Mosquitto
broker integration test (tests/test_router_echo_mosquitto_integration.py,
skipped automatically when Docker is unavailable).

controller/service.py

@@ -81,6 +81,7 @@ class ControllerService:
         self.mqtt = mqtt_adapter or MqttAdapter(
             config,
             events=self.events,
+            monotonic=monotonic,
         )
         self.downloads = download_manager
         self.playback = playback