docs(seedbox): add README for Portainer stack

seedbox/stacks/portainer/README.md

@@ -0,0 +1,52 @@
+# Portainer Stack
+
+Docker management UI, accessible via Tailscale.
+
+## Access
+
+- **URL**: https://portainer.taila5ad8.ts.net
+- **Initial setup**: Create admin account on first access
+
+## Ports
+
+| Port | Protocol | Exposure | Description |
+|------|----------|----------|-------------|
+| 9000 | TCP | Tailscale only | WebUI |
+
+## Features
+
+- View and manage all Docker containers
+- View logs in real-time
+- Execute commands in containers
+- Manage Docker networks and volumes
+- Deploy stacks from templates
+
+## First Setup
+
+1. Access https://portainer.taila5ad8.ts.net
+2. Create an admin account
+3. Select "Docker" as environment type
+4. Connect to local Docker socket
+
+## Troubleshooting
+
+```bash
+# Check logs
+docker logs portainer
+
+# Check Tailscale sidecar
+docker exec ts-portainer tailscale status
+
+# Restart stack
+cd /srv/seedbox/stacks/portainer
+docker compose restart
+```
+
+## Note
+
+Portainer is optional and mainly useful for:
+- Visual monitoring of containers
+- Quick access to logs
+- Emergency container management
+
+All deployments should still go through Gitea Actions for proper version control.