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/docs/internal/functional-tests/Restriction-TP/restriction02.md

@@ -0,0 +1,17 @@
+## RESTRICTION02: Domain name length
+
+### Test case identifier
+
+**RESTRICTION02:** Domain name length
+
+### Objective
+Section 3.1 of [RFC 1035](https://datatracker.ietf.org/doc/html/rfc1035) mentions that the
+the total length of a domain name (i.e., label octets and label length octets) 
+is restricted to 255 octets or less.
+
+The objective for this test is verify whether the engine conforms to the
+specification described in the previous paragraph
+
+### Results
+Since it is not possible to fit in more than 255 octets in a DNS 
+packet, this test is not run.