Revert "monitoring: run node_exporter on host network"

This reverts commit d48713cb15.

monitoring.yml

@@ -210,10 +210,6 @@ services:
   nodeexporter:
     image: prom/node-exporter
     container_name: nodeexporter
-    # Host network so the netdev collector (netlink) reads the HOST interfaces, not
-    # the container's idle veth — required for node_network_* (bandwidth) to be real.
-    # network_mode:host is exclusive with networks/expose, so those are removed.
-    network_mode: host
     volumes:
       - /proc:/host/proc:ro
       - /sys:/host/sys:ro
@@ -224,6 +220,10 @@ services:
       - '--path.sysfs=/host/sys'
       - '--collector.filesystem.ignored-mount-points=^/(sys|proc|dev|host|etc)($$|/)'
     restart: unless-stopped
+    expose:
+      - 9100
+    networks:
+      - chains
     labels:
       - "prometheus-scrape.enabled=true"
       - "prometheus-scrape.port=9100"