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/AUTHORS

@@ -0,0 +1,25 @@
+These people have contributed with code, documentation, specifications,
+bug reports, good ideas, clarifications and expertise to the Zonemaster
+project.
+
+From the Zonemaster team at AFNIC and IIS:
+
+Sandoche Balakrichenan
+Stephane Bortzmeyer
+Mats Dufberg
+Calle Dybedahl
+Anne-Marie Eklund Löwinder
+Paul Hoffman
+Vincent Levigneron
+Einar Lönn
+Samia M'timet
+Erika Olsson
+Jakob Schlyter
+Mohsen Souissi
+Michal Toma
+Patrik Wallström
+
+Other contributors:
+
+Arsen Stasic
+Yann 'Ze' Richard