feat: standalone node-exporter + telegraf compose per node

Post-Swarm: node-exporter must run standalone with pid:host, since Swarm mode
blocked it and cross-node /proc namespaces contaminated swap metrics. Marks the
stacks/ definition superseded.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

stacks/node-exporter/docker-compose.yml

@@ -1,7 +1,16 @@
+# SUPERSEDED 2026-03-21: Do NOT deploy this as a Swarm stack.
+# Swarm mode blocks pid: host, causing cross-node /proc namespace contamination
+# where node-exporter reads wrong host's memory metrics.
+# Use standalone Compose on each node instead:
+#   compose/hf-pdocker-01/node-exporter/docker-compose.yml
+#   compose/hf-pdocker-02/node-exporter/docker-compose.yml
+#   compose/bart/node-exporter/docker-compose.yml
+
 services:
   node-exporter:
-    image: prom/node-exporter:latest
+    image: prom/node-exporter:v1.7.0
     hostname: "{{.Node.Hostname}}"
+    pid: host
     ports:
       - "9100:9100"
     volumes:
@@ -12,6 +21,7 @@ services:
       - '--path.procfs=/host/proc'
       - '--path.rootfs=/rootfs'
       - '--path.sysfs=/host/sys'
+      - '--collector.filesystem.mount-points-exclude=^/(sys|proc|dev|host|etc)($$|/)'
     logging:
       driver: "json-file"
       options: