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/Nameserver-TP/nameserver07.md

@@ -0,0 +1,34 @@
+## NAMESERVER07:  To check whether authoritative name servers return an upward referral
+
+### Test case identifier
+NAMESERVER07 To check whether authoritative name servers return an upward
+referral
+
+
+### Objective
+The configuration and/or implementation of some authoritative name servers
+causes them to return an upward referral to the root zone. There are proofs that
+such a [behaviour could be used for DDoS attacks](
+https://www.dns-oarc.net/oarc/articles/upward-referrals-considered-harmful)
+
+
+### Inputs
+The domain name to be tested.
+
+### Ordered description of steps to be taken to execute the test case
+1. If the input domain to be tested is the root, exit from the test.
+2. Retrieve all address records for all the name servers using [Method 
+   4](../Methods.md) and [Method 5](../Methods.md).
+3. An NS query is sent to each name server IP address found in step 2,
+   with the root “.” as the destination 
+4. If any of the query returns with one or more responses in the
+   authority section, then this test case fails.
+
+### Outcome(s)
+The test case is Ok only if there are no responses in the authority section 
+
+### Special procedural requirements
+None.
+
+### Intercase dependencies
+None.