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/Zone-TP/README.md

@@ -0,0 +1,27 @@
+# Zone Test Plan
+
+These are tests of the zone content in DNS, such as SOA and MX records.
+
+This document uses the terminology defined in the [Master Test Plan].
+
+
+[Master Test Plan]:             ../MasterTestPlan.md
+[Test Case README]:             ../README.md
+
+<!-- Content until EOF generated by script updateTestPlanReadme.pl from Zonemaster/Zonemaster utils directory -->
+
+## Test cases list
+
+|Test Case |Test Case Description|
+|:---------|:--------------------|
+|[ZONE01](zone01.md)|Fully qualified master nameserver in SOA|
+|[ZONE02](zone02.md)|SOA 'refresh' minimum value|
+|[ZONE03](zone03.md)|SOA 'retry' lower than 'refresh'|
+|[ZONE04](zone04.md)|SOA 'retry' at least 1 hour|
+|[ZONE05](zone05.md)|SOA 'expire' minimum value|
+|[ZONE06](zone06.md)|SOA 'minimum' maximum value|
+|[ZONE07](zone07.md)|SOA master is not an alias|
+|[ZONE08](zone08.md)|MX is not an alias|
+|[ZONE09](zone09.md)|MX record present|
+|[ZONE10](zone10.md)|No multiple SOA records|
+|[ZONE11](zone11.md)|SPF policy validation|