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/DNSSEC-TP/dnssec12.md

@@ -0,0 +1,40 @@
+## DNSSEC12: Test for DNSSEC Algorithm Completeness
+
+### Test case identifier
+**DNSSEC12** Test for DNSSEC Algorithm Completeness
+
+### Objective
+
+The objectives for this Test Case has yet to be defined. This is a
+placeholder for a complete definition of the Test Case. The Test Case
+is not yet implemented.
+
+Test for DNSSEC Algorithm Completeness (DS->DNSKEY->RRSIG)
+
+See issues [#588], [#528], [#529] and [#231].
+
+[#588]: https://github.com/zonemaster/zonemaster/issues/588
+[#528]: https://github.com/zonemaster/zonemaster/issues/528
+[#529]: https://github.com/zonemaster/zonemaster/issues/529
+[#231]: https://github.com/zonemaster/zonemaster/issues/231
+
+
+### Inputs
+
+TBD.
+
+### Ordered description of steps to be taken to execute the test case
+
+TBD.
+
+### Outcome(s)
+
+TBD.
+
+### Special procedural requirements
+
+TBD.
+
+### Intercase dependencies
+
+TBD.