feat: Add stack.toml metadata files for Komodo recognition

Added stack.toml files for all stacks:
- monitoring/prometheus/stack.toml
- monitoring/grafana/stack.toml
- monitoring/node-exporter/stack.toml
- communication/gotify/stack.toml
- communication/vaultwarden/stack.toml

Each stack.toml contains:
- Stack metadata (name, description, version, category)
- Compose file reference
- Secret variables
- Port mappings
- Volume definitions
- Network configuration
- Healthcheck settings

stacks/monitoring/node-exporter/stack.toml

@@ -0,0 +1,25 @@
+[stack]
+name = "Node Exporter"
+description = "System-Metriken für Prometheus"
+version = "1.0.0"
+category = "monitoring"
+
+[compose]
+file = "compose.yml"
+
+[variables]
+# Keine Secrets erforderlich
+
+[ports]
+internal = 9100
+external = "127.0.0.1:9100"
+description = "Node Exporter Metrics"
+
+[networks]
+monitoring = "bridge"
+
+[healthcheck]
+endpoint = "http://localhost:9100/metrics"
+interval = "30s"
+timeout = "10s"
+retries = 3