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-backend/README.md

@@ -0,0 +1,68 @@
+# Zonemaster Backend
+
+### Purpose
+This repository is one of the components of the Zonemaster software. For an
+overview of the Zonemaster software, please see the
+[Zonemaster repository].
+
+This module is the Backend JSON/RPC weservice for the Web Interface part of
+the Zonemaster project. It offers a JSON/RPC api to run tests one by one
+(as the zonemaster-gui web frontend module does, or by using a batch API to
+run the Zonemaster engine on many domains)
+
+A Zonemaster user needs to install the backend only in the case where there is a
+need of logging the Zonemaster test runs in one's own respective database for
+analysing.
+
+
+### Prerequisites
+
+Before you install the Zonemaster Backend, you need the
+Zonemaster Engine installed. Please see the
+[Zonemaster Engine installation instructions][Zonemaster-Engine installation].
+
+
+### Upgrade
+
+See the [upgrade document].
+
+
+### Installation
+
+Follow the detailed [installation instructions].
+
+
+### Configuration
+
+See the [configuration documentation].
+
+
+### Documentation
+
+The Zonemaster Backend documentation is split up into several documents:
+
+* A number of [Typographic Conventions] are used throughout this documentation.
+* The [Architecture] document describes each of the Zonemaster Backend
+  components and how they operate. It also discusses all central concepts
+  needed to understand the Zonemaster backend, and contains a glossary over
+  domain specific technical terms.
+* The [Getting Started] guide walks you through creating a *test* and following
+  it through its life cycle, all using JSON-RPC calls to the *RPC API daemon*.
+* The [API] documentation describes the *RPC API daemon* inteface in detail.
+
+
+## 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 respository.
+
+
+[API]:                            https://github.com/zonemaster/zonemaster/blob/master/docs/public/using/backend/rpcapi-reference.md
+[Architecture]:                   docs/Architecture.md
+[Configuration documentation]:    https://github.com/zonemaster/zonemaster/blob/master/docs/public/configuration/backend.md
+[Getting Started]:                https://github.com/zonemaster/zonemaster/blob/master/docs/public/using/backend/getting-started.md
+[Installation instructions]:      https://github.com/zonemaster/zonemaster/blob/master/docs/public/installation/zonemaster-backend.md
+[Typographic Conventions]:        docs/TypographicConventions.md
+[Upgrade document]:               https://github.com/zonemaster/zonemaster/blob/master/docs/public/upgrading/backend.md
+[Zonemaster-Engine installation]: https://github.com/zonemaster/zonemaster/blob/master/docs/public/installation/zonemaster-engine.md
+[Zonemaster repository]:          https://github.com/zonemaster/zonemaster