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/communication/gotify/compose.yml

@@ -0,0 +1,27 @@
+services:
+  gotify:
+    image: gotify/server:latest
+    container_name: gotify
+    restart: unless-stopped
+    ports:
+      - "127.0.0.1:9091:80"
+    volumes:
+      - gotify_data:/app/data
+    environment:
+      - GOTIFY_DEFAULTUSER_NAME=${SECRET:gotify-admin-user}
+      - GOTIFY_DEFAULTUSER_PASS=${SECRET:gotify-admin-pass}
+    networks:
+      - gotify-network
+    healthcheck:
+      test: ["CMD", "wget", "--spider", "-q", "http://localhost:80/health"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 10s
+
+volumes:
+  gotify_data:
+
+networks:
+  gotify-network:
+    driver: bridge