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/test-zone-data/Zone-TP/zone11/README.md

@@ -0,0 +1,13 @@
+[This directory], i.e. the same directory as this README file, holds zone
+files and configuration files to implement the test zones for the scenarios
+defined in [Zone11 test scenario specification].
+
+For these test zones the following files are found in [this directory]:
+* Zone files for `zone11.xa` and other related zones;
+* CoreDNS configuration file;
+* Output from `zonemaster-cli` on all test scenarios in
+  [Zone11 Test Zones Output].
+
+[Zone11 Test Zones Output]:                   ./test-zones-output.md
+[Zone11 test scenario specification]:         ../../../docs/public/specifications/test-zones/Zone-TP/zone11.md
+[This directory]:                             .