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

monitoring/docker-compose.yaml

@@ -0,0 +1,59 @@
+name: monitoring
+
+services:
+  prometheus:
+    image: prom/prometheus:v3.4.0
+    container_name: prometheus
+    restart: unless-stopped
+    ports:
+      - "9090:9090"
+    command:
+      - '--config.file=/etc/prometheus/prometheus.yml'
+      - '--storage.tsdb.path=/prometheus'
+      - '--storage.tsdb.retention.time=90d'
+      - '--web.enable-lifecycle'
+    volumes:
+      - /mnt/tank/docker/appdata/prometheus:/prometheus
+      - /mnt/docker-ssd/docker/compose/monitoring/prometheus.yml:/etc/prometheus/prometheus.yml:ro
+    networks:
+      - default
+
+  grafana:
+    image: grafana/grafana:13.0.1
+    container_name: grafana
+    restart: unless-stopped
+    ports:
+      - "3000:3000"
+    environment:
+      TZ: ${TZ}
+      GF_SECURITY_ADMIN_USER: ${GF_ADMIN_USER}
+      GF_SECURITY_ADMIN_PASSWORD: ${GF_ADMIN_PASS}
+      GF_SERVER_ROOT_URL: https://${GF_HOST}/
+    volumes:
+      - /mnt/tank/docker/appdata/grafana:/var/lib/grafana
+      - /mnt/docker-ssd/docker/compose/monitoring/provisioning:/etc/grafana/provisioning:ro
+    networks:
+      - pangolin
+      - default
+
+  node-exporter:
+    image: prom/node-exporter:v1.9.0
+    container_name: node-exporter
+    restart: unless-stopped
+    ports:
+      - "9100:9100"
+    command:
+      - '--path.procfs=/host/proc'
+      - '--path.sysfs=/host/sys'
+      - '--path.rootfs=/rootfs'
+      - '--collector.filesystem.mount-points-exclude=^/(sys|proc|dev|host|etc)($$|/)'
+    volumes:
+      - /proc:/host/proc:ro
+      - /sys:/host/sys:ro
+      - /:/rootfs:ro
+    networks:
+      - default
+
+networks:
+  pangolin:
+    external: true