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/Behavior-TP/behavior03.md

@@ -0,0 +1,44 @@
+## BEHAVIOR03: The behavior of the engine when IPv6 or IPv4 is disabled
+
+### Test case identifier
+
+**BEHAVIOR03:** The behavior of the engine when IPv6 or IPv4 is disabled
+
+### Objective 
+This test is to verify whether appropriate results are displayed when
+querying a domain name from the CLI with IPv6 or IPv4 disabled.
+
+### Inputs
+
+The domain to be tested.
+
+### Ordered description of steps to be taken to execute the test case
+
+1. A valid domain is verified with corresponding options "--no-ipv6" or "--no-ipv4" using Zonemaster CLI
+2. If the query don’t receive a CRITICAL or ERROR notice, the test returns PASS
+
+### Results
+
+Verifying a valid zone with either IPv4 or IPV6 disabled using the zonemaster
+CLI does provide expected results without false positive or false negative as
+seen in the appendix. 
+
+### Appendix
+```
+zonemaster-cli --no-ipv6 afnic.fr
+Seconds Level     Message
+======= ========= =======
+   2.30 NOTICE    IPv6 is disabled, not sending "NS" query to
+ns1.nic.fr/2001:660:3003:2::4:1.
+   2.30 NOTICE    IPv6 is disabled, not sending "NS" query to
+ns2.nic.fr/2001:660:3005:1::1:2.
+   2.31 NOTICE    IPv6 is disabled, not sending "NS" query to
+ns3.nic.fr/2001:660:3006:1::1:1.
+   7.65 NOTICE    SOA 'mname' nameserver (dnsmaster.nic.fr) is not listed in
+"parent" NS records for tested zone (ns1.nic.fr;ns2.nic.fr;ns3.nic.fr).
+   7.65 NOTICE    SOA 'refresh' value (7200) is less than the recommended one
+(14400).
+   7.65 NOTICE    SOA 'retry' value (1800) is less than the recommended one
+(3600).
+
+```