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/astro.config.mjs

@@ -0,0 +1,54 @@
+// @ts-check
+import { defineConfig } from 'astro/config';
+import remarkGfm from 'remark-gfm';
+import {
+    remarkDefinitionList,
+    defListHastHandlers,
+} from "remark-definition-list";
+import svelte from '@astrojs/svelte';
+import node from '@astrojs/node';
+import config from './src/config.js';
+import messagesPlugin, { messagesIntegration } from './scripts/messages-plugin.ts';
+
+// https://astro.build/config
+export default defineConfig({
+    base: config.baseUrl,
+    trailingSlash: "always",
+    output: process.env.NODE_ENV === 'production' ? 'static' : 'server',
+
+    outDir: './public/dist',
+    publicDir: './static',
+
+    i18n: {
+        locales: config.enabledLanguages,
+        defaultLocale: config.defaultLanguage,
+        routing: {
+            prefixDefaultLocale: true
+        },
+    },
+
+    markdown: {
+        remarkPlugins: [remarkGfm, remarkDefinitionList],
+        remarkRehype: { handlers: defListHastHandlers },
+    },
+
+    integrations: [
+        svelte({
+            compilerOptions: {
+                customElement: true
+            }
+        }),
+        messagesIntegration()
+    ],
+
+    vite: {
+        plugins: [messagesPlugin({
+            defaultLanguage: config.defaultLanguage,
+            enabledLanguages: config.enabledLanguages,
+        })],
+    },
+
+    adapter: process.env.NODE_ENV === 'production' ? undefined : node({
+        mode: 'standalone'
+    }),
+});