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/zone11.arpa.zone

@@ -0,0 +1,21 @@
+$ORIGIN zone11.arpa.
+$TTL 3600
+
+@                          SOA    ns1.zone11.xa. admin.zone11.xa. (
+                                  2025080400      ; serial
+                                  6h              ; refresh
+                                  1h              ; retry
+                                  1w              ; expire
+                                  1d )            ; minimum
+
+                           NS     ns1.zone11.xa.
+                           NS     ns2.zone11.xa.
+
+no-spf-arpa-zone           NS     ns1.child.zone11.xa.
+                           NS     ns2.child.zone11.xa.
+
+null-spf-arpa-zone         NS     ns1.child.zone11.xa.
+                           NS     ns2.child.zone11.xa.
+
+non-null-spf-arpa-zone     NS     ns1.child.zone11.xa.
+                           NS     ns2.child.zone11.xa.