feat: add full Zonemaster stack with Docker and Spanish UI

- Clone all 5 Zonemaster component repos (LDNS, Engine, CLI, Backend, GUI)
- Dockerfile.backend: 8-stage multi-stage build LDNS→Engine→CLI→Backend
- Dockerfile.gui: Astro static build served via nginx
- docker-compose.yml: backend (internal) + frontend (port 5353)
- nginx.conf: root redirects to /es/, /api/ proxied to backend
- zonemaster-gui/config.ts: defaultLanguage set to 'es' (Spanish)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

zonemaster-gui/README.md

@@ -0,0 +1,58 @@
+# Zonemaster Web GUI [![CI status](https://github.com/zonemaster/zonemaster-gui/actions/workflows/ci.yml/badge.svg)](https://github.com/zonemaster/zonemaster-gui/actions/workflows/ci.yml)
+
+## Overview
+
+Zonemaster GUI is the web interface component of the Zonemaster project, a tool designed for DNS validation and testing. For a comprehensive overview of the Zonemaster software, please see the [Zonemaster repository].
+
+## Prerequisites
+
+Before installing the Zonemaster GUI, ensure you have the Zonemaster Engine and Zonemaster-Backend setup. Refer to the [Zonemaster-Engine installation] and [Zonemaster-Backend installation] documents.
+
+## Installation
+
+There are two ways to install the Zonemaster GUI:
+
+### Quick Install (1 minute)
+Download the release zip file, upload to your web server, and configure. 
+
+### Full Customization (5 minutes)
+Clone the repository, build, and deploy.
+
+For detailed instructions, see [INSTALL.md](docs/INSTALL.md).
+
+## Development
+
+To set up your development environment:
+
+1. Clone the repository
+2. Run `npm install`
+3. Run `cp .env.example .env`
+4. Set the URL to your Zonemaster backend in the `.env` file
+5. Run `npm run dev`
+
+## Documentation
+
+Refer to the [docs](/docs) directory for detailed information on:
+- Installation and configuration
+- Theming and customization
+- Translation guide
+- Testing
+- UI documentation
+
+For contribution guidelines, see [CONTRIBUTE.md](CONTRIBUTE.md).
+
+## License
+
+This is free software under a 2-clause BSD license. The full text of the license can be found in the [LICENSE](LICENSE) file included in this repository.
+
+Images `src/assets/images/person_looking_at_computer.svg` and `src/assets/images/world_connected.svg` are taken from <https://undraw.co>, [full license](https://undraw.co/license).
+
+Images `src/assets/images/person_looking_at_computer.svg` and `src/assets/images/world_connected.svg` are taken from <https://undraw.co>, [full license](https://undraw.co/license).
+
+[Backend Configuration]:            https://github.com/zonemaster/zonemaster/blob/master/docs/public/configuration/backend.md
+[GUI Configuration]:                https://github.com/zonemaster/zonemaster/blob/master/docs/public/configuration/gui.md
+[Installation instructions]:        https://github.com/zonemaster/zonemaster/blob/master/docs/public/installation/zonemaster-gui.md
+[Public documentation]:             https://github.com/zonemaster/zonemaster/blob/master/docs/public/README.md
+[Zonemaster-Engine installation]:   https://github.com/zonemaster/zonemaster/blob/master/docs/public/installation/zonemaster-engine.md
+[Zonemaster-Backend installation]:  https://github.com/zonemaster/zonemaster/blob/master/docs/public/installation/zonemaster-backend.md
+[Zonemaster repository]:            https://github.com/zonemaster/zonemaster