added Docker image build to Gitea

docker/Dockerfile

@@ -0,0 +1,21 @@
+FROM alpine:latest AS base-release
+RUN --mount=type=cache,target=/var/cache/apk apk update
+RUN --mount=type=cache,target=/var/cache/apk apk add openjdk21-jre
+RUN adduser -D luser
+USER luser
+WORKDIR /home/luser
+
+FROM base-release AS release
+ADD gbcs-cli-envelope-*.jar gbcs.jar
+ENTRYPOINT ["java", "-jar", "/home/luser/gbcs.jar"]
+
+FROM base-release AS release-memcached
+ADD --chown=luser:luser gbcs-cli-envelope-*.jar gbcs.jar
+RUN mkdir plugins
+WORKDIR /home/luser/plugins
+RUN --mount=type=bind,source=.,target=/build/distributions tar -xf /build/distributions/gbcs-memcached*.tar
+WORKDIR /home/luser
+ENTRYPOINT ["java", "-jar", "/home/luser/gbcs.jar"]
+
+FROM release-memcached as compose
+COPY --chown=luser:luser conf/gbcs-memcached.xml /home/luser/.config/gbcs/gbcs.xml