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/root-null-spf.zone

@@ -0,0 +1,20 @@
+$ORIGIN .
+$TTL 3600
+
+@       SOA     ns1.null-spf.root-servers.zone11.xa. admin.zone11.xa. (
+                2025080400      ; serial
+                6h              ; refresh
+                1h              ; retry
+                1w              ; expire
+                1d )            ; minimum
+
+        NS      ns1.null-spf.root-servers.zone11.xa.
+        NS      ns2.null-spf.root-servers.zone11.xa.
+
+        TXT     "v=spf1 -all"
+
+ns1.null-spf.root-servers.zone11.xa.  A      127.19.11.43
+                                      AAAA   fda1:b2:c3::127:19:11:43
+ns2.null-spf.root-servers.zone11.xa.  A      127.19.11.44
+                                      AAAA   fda1:b2:c3::127:19:11:44
+