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-ldns/t/utils.t

@@ -0,0 +1,22 @@
+use Test::More;
+
+BEGIN { use_ok( 'Zonemaster::LDNS' ) }
+
+SKIP: {
+    skip 'no network', 5 unless $ENV{TEST_WITH_NETWORK};
+
+    my $res = new_ok( 'Zonemaster::LDNS', ['8.8.4.4'] );
+
+    my @addrs = sort $res->name2addr( 'b.ns.se' );
+    my $count = $res->name2addr( 'b.ns.se' );
+
+    is_deeply( \@addrs, [ "192.36.133.107", "2001:67c:254c:301::53" ], 'expected addresses' );
+    is( $count, 2, 'expected count' );
+
+    my @names = sort $res->addr2name( '8.8.8.8' );
+    $count = $res->addr2name( '8.8.8.8' );
+    is_deeply( [map {lc($_)} @names], ['dns.google.'], 'expected names' );
+    is( $count, 1, 'expected name count' );
+}
+
+done_testing;