feat: Initial stacks for testing

Added first test stacks:
- monitoring/prometheus
- monitoring/grafana
- monitoring/node-exporter
- communication/gotify
- communication/vaultwarden

All stacks:
- Use localhost ports only (for Caddy reverse proxy)
- Support Komodo Secrets via ${SECRET:secret-name}
- Include README with Caddy integration instructions
- Ready for Komodo v2 Resource Sync

stacks/monitoring/node-exporter/compose.yml

@@ -0,0 +1,28 @@
+services:
+  node-exporter:
+    image: prom/node-exporter:latest
+    container_name: node-exporter
+    restart: unless-stopped
+    ports:
+      - "127.0.0.1:9100:9100"
+    volumes:
+      - /proc:/host/proc:ro
+      - /sys:/host/sys:ro
+      - /:/rootfs:ro
+    command:
+      - '--path.procfs=/host/proc'
+      - '--path.sysfs=/host/sys'
+      - '--path.rootfs=/rootfs'
+      - '--collector.filesystem.mount-points-exclude=^/(sys|proc|dev|host|etc)($$|/)'
+    networks:
+      - monitoring
+    healthcheck:
+      test: ["CMD", "wget", "--spider", "-q", "http://localhost:9100/metrics"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 10s
+
+networks:
+  monitoring:
+    driver: bridge