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/prometheus/docker-compose.yml

@@ -0,0 +1,8 @@
+services:
+  prometheus:
+    image: prom/prometheus
+    volumes:
+      - "/home/server-admin/prometheus/prometheus.yml:/etc/prometheus/prometheus.yml"
+      - "/home/server-admin/prometheus/data:/prometheus"
+    ports:
+      - 9090:9090

monitoring/prometheus/prometheus.yml

@@ -0,0 +1,17 @@
+scrape_configs:
+  - job_name: 'pve'
+    static_configs:
+      - targets:
+        - 192.168.2.100 # Proxmox VE Node
+    metrics_path: /pve
+    params:
+      module: [default]
+      cluster: ['1']
+      node: ['1']
+    relabel_configs:
+      - source_labels: [__address__]
+        target_label: __param_target
+      - source_labels: [__param_target]
+        target_label: instance
+      - target_label: __address__
+        replacement: 192.168.2.114:9221 #PVE Exporter Address