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/prometheus/README.md

@@ -0,0 +1,69 @@
+# Prometheus
+
+📊 **Monitoring & Alerting**
+
+Prometheus ist ein Open-Source-Monitoring- und Alerting-System.
+
+---
+
+## 🚀 Quick Start
+
+1. **In Komodo:** Stack auswählen → Deploy
+2. **Server wählen**
+3. **Warten** bis Container läuft
+4. **Caddy Config** hinzufügen
+5. **Öffnen** unter `prometheus.example.com`
+
+---
+
+## 🔧 Caddy Integration
+
+```bash
+ssh <server>
+sudo nano /etc/caddy/Caddyfile
+```
+
+Hinzufügen:
+```caddyfile
+prometheus.example.com {
+    reverse_proxy localhost:9090
+}
+```
+
+```bash
+sudo systemctl reload caddy
+```
+
+---
+
+## 🔐 Secrets (Komodo)
+
+Keine Secrets erforderlich für Basis-Installation.
+
+---
+
+## 📁 Files
+
+- `compose.yml` - Docker Compose Konfiguration
+
+---
+
+## 📊 Prometheus UI
+
+- **URL:** http://localhost:9090
+- **Query Browser:** `/graph`
+- **Alerts:** `/alerts`
+- **Targets:** `/targets`
+
+---
+
+## 🔄 Updates
+
+Prometheus wird automatisch aktuell gehalten durch Komodo.
+
+---
+
+## 📞 Support
+
+- **Docs:** https://prometheus.io/docs
+- **GitHub:** https://github.com/prometheus/prometheus