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/share/zm-rpcapi.service

@@ -0,0 +1,13 @@
+[Unit]
+Description=RPC server for Zonemaster Backend
+After=network.target mariadb.service postgresql.service
+Wants=mariadb.service postgresql.service
+
+[Service]
+Type=simple
+ExecStart=/usr/local/bin/starman --listen=127.0.0.1:5000 --preload-app --user=zonemaster --group=zonemaster --pid=/run/zonemaster/zm-rpcapi.pid --error-log=/var/log/zonemaster/zm-rpcapi.log --daemonize /usr/local/bin/zonemaster_backend_rpcapi.psgi
+KillSignal=SIGQUIT
+PIDFile=/run/zonemaster/zm-rpcapi.pid
+
+[Install]
+WantedBy=multi-user.target