feat(monitoring): add Prometheus/Grafana monitoring stack

- Add Grafana dashboard service (port 3000)
- Add Prometheus time-series database (port 9090)
- Add PVE Exporter for Proxmox metrics (port 9221)
- Deploy on VM 101 (monitoring-docker) at 192.168.2.114
- Configure scraping for Proxmox node 192.168.2.100
- Add docker-compose configurations for all services
- Add template files for sensitive credentials (pve.yml.template, .env.template)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

monitoring/grafana/docker-compose.yml

@@ -0,0 +1,9 @@
+services:
+  grafana:
+    image: grafana/grafana-enterprise
+    container_name: grafana
+    restart: unless-stopped
+    ports:
+      - "3000:3000"
+    volumes:
+      - "/home/server-admin/grafana/grafana-storage:/var/lib/grafana"