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/public/specifications/tests/Syntax-TP/syntax01.md

@@ -0,0 +1,38 @@
+## SYNTAX01: No illegal characters in the domain name
+
+### Test case identifier
+**SYNTAX01** No illegal characters in the domain name
+
+### Objective
+
+There must be no illegal characters used in the domain name.
+The domain name must follow the rules defined in section 2.3.1 of
+[RFC 1035](https://datatracker.ietf.org/doc/html/rfc1035),
+section 2.1 of [RFC 1123](https://datatracker.ietf.org/doc/html/rfc1123#section-2.1),
+section 11 of
+[RFC 2182](https://datatracker.ietf.org/doc/html/rfc2181#section-11) and section 2 of
+[RFC 3696](https://datatracker.ietf.org/doc/html/rfc3696#section-2).
+
+### Inputs
+
+The domain name to be tested.
+
+### Ordered description of steps to be taken to execute the test case
+
+1. The domain name of the test object is used as the input for the
+   validation.
+2. Check for characters that are not allowed in the domain name according
+   to the rules defined in section 2.3.1 of
+   [RFC 1035](https://datatracker.ietf.org/doc/html/rfc1035).
+
+### Outcome(s)
+
+If there are any invalid characters in the domain name, this test case fails.
+
+### Special procedural requirements
+
+None.
+
+### Intercase dependencies
+
+None.