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

justfile

@@ -132,7 +132,28 @@ restart SERVICE:
 
 # Restart the full stack
 restart-all:
-    ssh {{RPI_HOST}} 'docker restart mosquitto zigbee2mqtt nodered'
+    ssh {{RPI_HOST}} 'docker restart mosquitto zigbee2mqtt nodered doorbell-listener'
+
+# Tail doorbell-listener container logs
+doorbell-logs:
+    ssh {{RPI_HOST}} 'docker logs --tail 50 -f doorbell-listener'
+
+# Restart just the doorbell-listener
+restart-doorbell:
+    ssh {{RPI_HOST}} 'docker restart doorbell-listener'
+
+# Publish a test alert to ntfy (used for E2E testing the listener).
+# Usage: just doorbell-publish "Title" "Body"
+doorbell-publish TITLE BODY="Someone is at the door":
+    curl -sS -X POST "https://ntfy.sh/ALERT_klubhaus_topic_test" \
+        -H "Title: {{TITLE}}" \
+        -H "Priority: high" \
+        -d "{{BODY}}" \
+        -w "\nHTTP %{http_code}\n"
+
+# Build + (re)start the listener (after edits to infra/doorbell-listener/)
+doorbell-rebuild:
+    ssh {{RPI_HOST}} 'cd {{RPI_DIR}}/nr-flow-validator && docker compose build doorbell-listener && docker compose up -d doorbell-listener'
 
 # Show paired zigbee devices and their friendly names
 z2m-devices: