Add doorbell-listener: ntfy → zigbee2mqtt Sideboard Lamp toggle

Polls ntfy.sh for ALERT_klubhaus_topic(_test) and publishes
{state: TOGGLE} to zigbee2mqtt/Sideboard Lamp/set on each new
message event. Dual-topic subscription so switching from test to
production requires no code change; sender still uses test topic.

- infra/doorbell-listener/: uv-based Docker service (arm64)
- compose: depends_on mosquitto, persists last_id per topic
- justfile: doorbell-publish, doorbell-logs, doorbell-rebuild,
  restart-all now includes doorbell-listener

README.md

@@ -32,8 +32,9 @@ All diagnostic commands live in the justfile. Run `just --list` to see them.
 - `just mqtt-button [action]` — E2E test: publish a button action and watch which `/set` topics fire
 - `just z2m-devices` — paired zigbee devices + group membership
 - `just mqtt-pub TOPIC PAYLOAD` / `just mqtt-sub TOPIC` / `just mqtt-watch` — raw MQTT
-- `just nr-logs` / `just z2m-logs` / `just mqtt-logs` — container log tails
+- `just nr-logs` / `just z2m-logs` / `just mqtt-logs` / `just doorbell-logs` — container log tails
 - `just restart SERVICE` / `just restart-all` — docker restart
+- `just doorbell-publish "Title" "Body"` — publish a test alert to ntfy
 - `just rpi CMD` — run any command on the RPi over SSH
 
 `scripts/mqtt.py` and `scripts/diag.py` are the underlying helpers. Override the target host with `just RPI_HOST=user@host mqtt-button single`.