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/lib/Zonemaster/LDNS/RRList.pm

@@ -0,0 +1,100 @@
+package Zonemaster::LDNS::RRList;
+
+use strict;
+use warnings;
+
+use overload '<=>' => \&do_compare, 'cmp' => \&do_compare, '""' => \&to_string;
+
+sub do_compare {
+    my ( $self, $other, $swapped ) = @_;
+
+    return $self->compare( $other );
+}
+
+sub to_string {
+    my ( $self ) = @_;
+
+    return $self->string;
+}
+
+1;
+
+=head1 NAME
+
+Zonemaster::LDNS::RRList - class representing lists of resource records.
+
+=head1 SYNOPSIS
+
+    my $rrlist = Zonemaster::LDNS::RRList->new( $rrs_aref );
+
+=head1 CLASS METHODS
+
+=over
+
+=item new()
+
+Creates a new empty L<Zonemaster::LDNS::RRList> object.
+
+=item new($rrs)
+
+Creates a new L<Zonemaster::LDNS::RRList> object for the given resource records.
+
+Takes a reference to an array of L<Zonemaster::LDNS::RR> objects.
+
+Returns a L<Zonemaster::LDNS::RRList> object.
+
+=back
+
+=head1 INSTANCE METHODS
+
+=over
+
+=item count()
+
+Returns the number of RRs in the list.
+
+=item compare($other)
+
+Compares two L<Zonemaster::LDNS::RRList>. The order of L<Zonemaster::LDNS::RR> objects in the list does not matter.
+The TTL field is ignored, and the comparison of domain names is case insensitive.
+
+Returns an integer, where 0 indicates equality.
+
+=item get($pos)
+
+    my $rr = Zonemaster::LDNS::RRList->get( 0 );
+
+Retrieves the RR in the given position from the list.
+
+Takes an integer.
+
+Returns a L<Zonemaster::LDNS::RR> object, or C<undef> if there was no RR.
+
+=item push($rr)
+
+Pushes an RR onto the list.
+
+=item pop()
+
+Pops an RR off the list.
+
+=item is_rrset()
+
+Returns true or false depending on if the list is an RRset or not.
+
+Note that the underlying LDNS function appears to have a bug as the comparison of the owner name field is case sensitive. See https://github.com/NLnetLabs/ldns/pull/251.
+
+=item string()
+
+Returns a string with the list of RRs in presentation format.
+
+=item do_compare($other)
+
+Calls the XS C<compare> method with the arguments it needs, rather than the ones overloading gives.
+
+=item to_string
+
+Calls the XS C<string> method with the arguments it needs, rather than the ones overloading gives. Functionally identical to L<string()> from the
+Perl level, except for being a tiny little bit slower.
+
+=back