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/Dockerfile

@@ -0,0 +1,76 @@
+FROM zonemaster/ldns:local AS build
+
+RUN apk add --no-cache \
+    # Only needed for CPAN deps
+    gcc \
+    make \
+    musl-dev \
+    perl-dev \
+    # Transitive deps included to improve build speed
+    perl-mailtools \
+    perl-module-build-tiny \
+    # Compile-time dependencies
+    perl-app-cpanminus \
+    perl-class-accessor \
+    perl-clone \
+    perl-file-sharedir \
+    perl-file-slurp \
+    perl-io-socket-inet6 \
+    perl-list-moreutils \
+    perl-locale-msgfmt \
+    perl-log-any \
+    perl-lwp-protocol-https \
+    perl-mail-spf \
+    perl-module-install \
+    perl-pod-coverage \
+    perl-readonly \
+    perl-sub-override \
+    perl-test-differences \
+    perl-test-exception \
+    perl-test-fatal \
+    perl-test-nowarnings \
+    perl-test-pod \
+    perl-text-csv \
+    perl-yaml \
+    perl-yaml-libyaml \
+ && cpanm --no-wget --from=https://cpan.metacpan.org/ \
+    Email::Valid \
+    List::Compare \
+    Locale::PO \
+    Locale::TextDomain \
+    Module::Find \
+    Net::IP::XS
+
+ARG version
+
+COPY ./Zonemaster-Engine-${version}.tar.gz ./Zonemaster-Engine-${version}.tar.gz
+
+RUN cpanm --notest --no-wget \
+    ./Zonemaster-Engine-${version}.tar.gz
+
+FROM zonemaster/ldns:local
+
+# Include all the Perl modules we built
+COPY --from=build /usr/local/lib/perl5/site_perl /usr/local/lib/perl5/site_perl
+COPY --from=build /usr/local/share/perl5/site_perl /usr/local/share/perl5/site_perl
+
+RUN apk add --no-cache \
+    # All the locales we need and more
+    musl-locales \
+    # Run-time dependencies
+    perl-class-accessor \
+    perl-clone \
+    perl-file-sharedir \
+    perl-file-slurp \
+    perl-io-socket-inet6 \
+    perl-list-moreutils \
+    perl-locale-msgfmt \
+    perl-log-any \
+    perl-mail-spf \
+    perl-mailtools \
+    perl-module-install \
+    perl-net-ip \
+    perl-readonly \
+    perl-text-csv \
+    perl-try-tiny \
+    perl-yaml-libyaml