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/test-zone-data/utils/sign-rrset

@@ -0,0 +1,99 @@
+#!/usr/bin/env perl
+
+=pod
+
+=head1 SUMMARY
+
+This script supports signing an RRset (one or more DNS records)
+by the provided private key
+
+=head1 SYNOPSIS
+
+cat data-file | sign-rrset.pl --key KEY --exp DATETIME --inc DATETIME
+
+sign-rrset.pl --help
+
+=over 3
+
+=item *
+KEY is the file with the private key matching the intended DNSKEY record.
+
+=item *
+DATETIME is the date-time in the format "YYYYMMDDHHMMSS" for RRSIG expiration (--exp)
+and RRSIG inception (--inc) respectively.
+
+=back
+
+=head1 DATA FILE
+
+Create a file with the complete RRset to be signed. You can freely add
+comment lines starting with "#" anywhere.
+
+=head1 EXAMPLE FILE
+
+=begin text
+
+err-mult-nsec-1.dnssec10.xa. 86400 IN	NSEC	ns1.err-mult-nsec-1.dnssec10.xa. NS SOA RRSIG NSEC DNSKEY TYPE65534
+err-mult-nsec-1.dnssec10.xa. 86400 IN	NSEC	www.err-mult-nsec-1.dnssec10.xa. NS SOA RRSIG NSEC DNSKEY TYPE65534
+
+=end text
+
+=cut
+
+
+use 5.16.0;
+use warnings;
+
+use Net::DNS::SEC 1.26;
+use Net::DNS 1.47;
+
+use Getopt::Long;
+use Pod::Usage;
+
+my ( $key, $exp, $inc, $help );
+GetOptions( 'key=s' => \$key,
+            'exp=s' => \$exp,
+            'inc=s' => \$inc,
+            'help'  => \$help
+          );
+
+if ( $help ) {
+    pod2usage(-verbose => 99);
+    exit 0;
+}
+
+unless ( $key ) {
+    say STDERR "Missing private key file";
+    say STDERR "Run with --help to get help";
+    exit 1;
+}
+
+unless ( $exp and $inc ) {
+    say STDERR "Missing expiration and/or inception value";
+    say STDERR "Run with --help to get help";
+    exit 1;
+}
+
+my @rrsetref; # List of references to RRs.
+
+while( my $line = <> ) {
+    chomp ( $line );
+    next if $line =~ /^\s*$/;
+    next if $line =~ /^#/;
+    my $rrref = Net::DNS::RR->new( $line );
+    push ( @rrsetref, $rrref );
+    
+}
+
+unless ( @rrsetref ) {
+    say "Missing RRset to sign";
+    say STDERR "Run with --help to get help";
+    exit 1;
+};
+
+my $private = Net::DNS::SEC::Private->new($key);
+
+my $sigrr= Net::DNS::RR::RRSIG->create( \@rrsetref, $private, sigex => $exp, sigin => $inc );
+
+say $sigrr->plain;
+