fix(monitoring): Linux-only exporters behind host-metrics profile; loki 3.5 key; prometheus joins shared network

- node-exporter + cadvisor need Linux rootfs mounts (fail on Docker
  Desktop) — moved to 'host-metrics' profile; VPS command updated
- loki 3.5: ingestion_burstsize_mb → ingestion_burst_size_mb
- prometheus joins erp_shared so job 'erp-api' resolves (verified: up=1)

monitoring/docker-compose.monitoring.yml

@@ -82,6 +82,7 @@ services:
       - prometheus_data:/prometheus
     networks:
       - monitoring
+      - shared
     restart: unless-stopped
 
   grafana:
@@ -130,10 +131,12 @@ services:
     restart: unless-stopped
 
   # -------------------------------------------------------------- exporters --
+  # Linux-host only (see cadvisor note): local runs skip it via the profile.
   node-exporter:
     image: prom/node-exporter:v1.9.1
     container_name: monitoring-node-exporter
     mem_limit: 32m
+    profiles: ["host-metrics"]
     command:
       - --path.rootfs=/host
     volumes:
@@ -155,10 +158,15 @@ services:
       - shared
     restart: unless-stopped
 
+  # Linux-host only: the rootfs bind mounts fail on Docker Desktop (Windows/macOS).
+  # VPS:   docker compose -f monitoring/docker-compose.monitoring.yml --env-file .env \
+  #          --profile host-metrics up -d
+  # Local: started WITHOUT the profile — per-container metrics are simply absent.
   cadvisor:
     image: gcr.io/cadvisor/cadvisor:v0.49.1
     container_name: monitoring-cadvisor
     mem_limit: 128m
+    profiles: ["host-metrics"]
     privileged: true
     devices:
       - /dev/kmsg