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-engine/t/po-files.t

@@ -0,0 +1,70 @@
+#!perl
+use v5.14.2;
+use strict;
+use warnings;
+use utf8;
+use Test::More; # see done_testing()
+
+use File::Basename qw( dirname );
+
+chdir dirname( dirname( __FILE__ ) ) or BAIL_OUT( "chdir: $!" );
+chdir 'share' or BAIL_OUT( "chdir: $!" );
+
+my $makebin = 'make';
+
+sub make {
+    my @make_args = @_;
+
+    undef $ENV{MAKEFLAGS};
+
+    my $command = join( ' ', $makebin, '--silent', '--no-print-directory', @make_args );
+    my $output = `$command`;
+
+    if ( $? == -1 ) {
+        BAIL_OUT( "failed to execute: $!" );
+    }
+    elsif ( $? & 127 ) {
+        BAIL_OUT( "child died with signal %d, %s coredump\n", ( $? & 127 ), ( $? & 128 ) ? 'with' : 'without' );
+    }
+
+    return $output, $? >> 8;
+}
+
+subtest "no fuzzy marks" => sub {
+    my ( $output, $status ) = make "show-fuzzy";
+    is $status, 0,  $makebin . ' show-fuzzy exits with value 0';
+    is $output, "", $makebin . ' show-fuzzy gives empty output';
+};
+
+subtest "check po files" => sub {
+    my ( $output, $status ) = make "check-po";
+    is $status, 0,  $makebin . ' check-po exits with value 0';
+    is $output, "", $makebin . ' check-po gives empty output';
+};
+
+subtest "check msg args" => sub {
+    my ( $output ) = make "check-msg-args";
+    is $output, "", $makebin . ' check-msg-args gives empty output';
+};
+
+subtest "tidy po files" => sub {
+    SKIP: {
+        my ( $output, $status );
+
+        $output = `git diff --numstat`;
+
+        skip 'git repo should be clean to run this test', 3 if $output ne '';
+
+        diag "Using msgcat version: " . `msgcat --version | head -n1`;
+
+        ( $output, $status ) = make "tidy-po";
+        is $status, 0,  $makebin . ' tidy-po exits with value 0';
+        is $output, "", $makebin . ' tidy-po gives empty output';
+
+        $output = `git diff --numstat`;
+        is $output, "", 'all files are tidied (if not run "make tidy-po")'
+            or diag `git diff`;
+    }
+};
+
+done_testing();