feat: Add 10 new stacks (Batch 1)

Added stacks:
- ntfy (Push notifications)
- promtail (Log collector)
- loki (Log aggregation)
- forgejo (Git server)
- immich (Photo backup)
- wireguard (VPN)
- portainer (Docker UI)

All stacks include:
- compose.yml with proper configuration
- README.md with deployment info
- stack.toml for Komodo Resource Sync

stacks/portainer/README.md

@@ -0,0 +1,19 @@
+# Portainer
+
+🐳 Docker Management UI
+
+## Deploy in Komodo
+
+**Pfad:** `stacks/portainer/`
+
+## Ports
+
+- `9000` - Web UI
+
+## Caddy
+
+```caddyfile
+portainer.example.com {
+    reverse_proxy localhost:9000
+}
+```