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/RR/RRSIG.pm

@@ -0,0 +1,91 @@
+package Zonemaster::LDNS::RR::RRSIG;
+
+use strict;
+use warnings;
+
+use parent 'Zonemaster::LDNS::RR';
+
+sub verify {
+    my ( $self, $rrset, $keys ) = @_;
+    my $msg = '';
+
+    return $self->verify_time( $rrset, $keys, time(), $msg );
+}
+
+sub verify_str {
+    my ( $self, $rrset, $keys ) = @_;
+    my $msg = '';
+
+    $self->verify_time( $rrset, $keys, time(), $msg );
+
+    return $msg;
+}
+
+1;
+
+=head1 NAME
+
+Zonemaster::LDNS::RR::RRSIG - Type RRSIG record
+
+=head1 DESCRIPTION
+
+A subclass of L<Zonemaster::LDNS::RR>, so it has all the methods of that class available in addition to the ones documented here.
+
+=head1 METHODS
+
+=over
+
+=item typecovered()
+
+Returns a string with the name of the RR type this signature covers.
+
+=item algorithm()
+
+Returns the algorithm number.
+
+=item labels()
+
+Returns the number of labels that was used to calculate the signature.
+
+=item origttl()
+
+Returns the original TTL value.
+
+=item expiration()
+
+Returns the expiration time, as a time_t.
+
+=item inception()
+
+Returns the inception time, as a time_t.
+
+=item keytag()
+
+Returns the keytag.
+
+=item signer()
+
+Returns the signer name.
+
+=item signature()
+
+Returns the cryptographic signture in binary form.
+
+=item verify($rrset_ref, $key_ref)
+
+Cryptographically verifies that the signature in this object matches the given RRset and at least one of the given keys. C<$rrset_ref> should be a
+reference to an array of RR objects, and C<$key_ref> a reference to an array of L<Zonemaster::LDNS::RR::DNSKEY> objects. This method simply returns a true
+or false value, depending on the result och the check.
+
+=item verify_str($rrset_ref, $key_ref)
+
+Takes exactly the same arguments as L<verify()> and performs the same action, but instead of true/false it returns a string describing the result.
+In the case of a successful result the message will be "All OK". For negative results, the string will describe the reason the verification failed.
+
+=item verify_time($rrset_ref, $key_ref, $time, $msg)
+
+This is the XS method doing the work for the previous two methods. C<$rrset_ref> and C<$key_ref> are the same as for the other methods. C<$time> is
+the C<time_t> value for which the validation should be made (for the previous two methods it is set to the current computer time). C<$msg> should be
+a writable scalar, and the string message describing the result will be but in it. The return value from the method is true/false.
+
+=back