Directive 1: voice intake watchdog (layer attribution, daily repeat, Apprise)

Build the Hub Fixes Directive 1 watchdog as a small standalone service on .13.

- Watch voice/audio_stream (paho); 15 min silence = 3 missed heartbeats.
- Attribute failures in order: broker -> voice_bridge -> ESP32/no-publisher.
  The ESP32 is never blamed when the broker or the bridge broke.
- Alert via Apprise on .35:8210 (tag sam_ntfy; daily repeat escalates to sam).
- Persist state; repeat once a day while broken; recovery notice; alerts stop.
- No auto-heal of any kind. Notification only.
- Require publisher evidence (heartbeat or retained presence) before treating
  silence as a failure, so the unflashed Directive 3 firmware cannot cause the
  cry-wolf false alarms the spec warns about.
- Docker: host network, read-only Docker socket, state volume, unless-stopped.
- 23 unit tests; live evidence captured in watchdog/README.md.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

watchdog/requirements.txt

@@ -0,0 +1 @@
+paho-mqtt==2.1.0