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/Engine/Recursor-PM/sub3.cname.recursor.engine.xa

@@ -0,0 +1,21 @@
+$TTL 3600
+$ORIGIN sub3.cname.recursor.engine.xa.
+
+@                          SOA  (
+                                   ns1
+                                   root
+                                   2023103100
+                                   86400
+                                   14400
+                                   3600000
+                                   3600
+                                 )
+
+@                          NS    ns1
+ns1                        A     127.30.1.33
+ns1                        AAAA  fda1:b2:c3:0:127:30:1:33
+
+
+; For scenario LOOPED-CNAME-OUT-OF-ZONE
+looped-cname-out-of-zone   CNAME   looped-cname-out-of-zone.sub2.cname.recursor.engine.xa.
+