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/docs/public/book.toml

@@ -0,0 +1,23 @@
+[book]
+authors = [ "Zonemaster Team" ]
+description = "Zonemaster documentation"
+language = "en"
+src = "./"
+
+[build]
+create-missing = false
+use-default-preprocessors = false
+
+[output.html]
+no-section-label = true
+
+[output.html.fold]
+enable = true
+level = 1
+
+[output.linkcheck]
+optional = true
+warning-policy= "warn"
+follow-web-links = false
+traverse-parent-directories = false
+exclude = [ 'SUMMARY.md', 'LICENSE.md', 'zonemaster_logo_2021_color.png', 'localhost' ]