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/DNSSEC-TP/dnssec10/Bind/zones/localhost.zone

@@ -0,0 +1,15 @@
+; For the dnssec10-37 view.
+;
+$TTL 604800
+@       SOA  localhost. root.localhost. (
+                   4    ; Serial
+              604800    ; Refresh
+               86400    ; Retry
+             2419200    ; Expire
+              604800 )  ; Negative Cache TTL
+;
+@       NS   localhost.
+@       A    127.0.0.1
+@       AAAA ::1
+@       TXT  "127.15.10.37 fda1:b2:c3:0:127:15:10:37"
+