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stacks/ definition superseded.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>

compose/bart/telegraf/docker-compose.yml

@@ -0,0 +1,22 @@
+services:
+  telegraf:
+    image: telegraf:latest
+    container_name: telegraf
+    hostname: bart
+    restart: unless-stopped
+    environment:
+      - HOST_PROC=/host/proc
+      - HOST_SYS=/host/sys
+      - HOST_ETC=/host/etc
+    volumes:
+      - /mnt/docker-data/configs/telegraf/telegraf.conf:/etc/telegraf/telegraf.conf:ro
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+      - /sys:/host/sys:ro
+      - /proc:/host/proc:ro
+      - /etc:/host/etc:ro
+    mem_limit: 512M
+    logging:
+      driver: "json-file"
+      options:
+        max-size: "50m"
+        max-file: "3"