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/Basic-TP/basic01/good-mixed-undel-2.basic01.xa.zone

@@ -0,0 +1,28 @@
+$ORIGIN good-mixed-undel-2.basic01.xa.            ; Must end with "."
+$TTL 3600
+
+@       SOA     ns1 admin. (
+                2024041902      ; serial
+                6h              ; refresh
+                1h              ; retry
+                1w              ; expire
+                1d )            ; minimum
+                
+
+@		NS	ns1
+@		NS	ns2
+ns1		A	127.12.1.31
+ns1		AAAA	fda1:b2:c3:0:127:12:1:31
+ns2		A	127.12.1.32
+ns2		AAAA	fda1:b2:c3:0:127:12:1:32
+
+
+$ORIGIN parent.good-mixed-undel-2.basic01.xa.            ; Must end with "."
+
+@		NS	ns1
+@		NS	ns6
+ns1		A	127.12.1.41
+ns1		AAAA	fda1:b2:c3:0:127:12:1:41
+ns6		A	127.12.1.46
+ns6		AAAA	fda1:b2:c3:0:127:12:1:46
+