Move reranker to Serenity, add monitoring and mesh-mqtt-observer stacks

- ai: remove reranker service (moved to Serenity at 10.5.1.5:9787)
- ai: add LiteLLM reranker proxy entry for Serenity
- ai: configure OpenWebUI to use LiteLLM for reranking
- monitoring: add Grafana + Prometheus stack
- mesh-mqtt-observer: add new service
- automation, documents, meshtastic: misc updates

mesh-mqtt-observer/docker-compose.yml

@@ -0,0 +1,24 @@
+services:
+  mesh-mqtt-observer:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    container_name: mesh-mqtt-observer
+    restart: unless-stopped
+    env_file:
+      - .env
+    volumes:
+      - /mnt/tank/docker/appdata/mesh-mqtt-observer:/data
+    networks:
+      - shared_postgres
+    healthcheck:
+      test: ["CMD", "python", "-m", "app.healthcheck"]
+      interval: 30s
+      timeout: 10s
+      retries: 5
+      start_period: 20s
+
+networks:
+  shared_postgres:
+    external: true
+    name: ${SHARED_POSTGRES_NETWORK}