change Dockerfile for kontor-spring to multistage and add kontor-javalin

kontor-javalin/Dockerfile

@@ -1,5 +1,28 @@
-FROM alpine/java:21-jdk
+# ----------------------------------------------------------------------- #
+FROM gradle:9.2.1-jdk AS builder
 WORKDIR /
-ADD build/libs/kontor-spring-0.2.0-SNAPSHOT.jar app.jar
-EXPOSE 8000
-CMD ["java", "-jar", "-Dspring.profiles.active=prod", "-Dvaadin.productionMode=true", "app.jar"]
+COPY ./api/src/main/ ./api/src/main/
+COPY ./api/build.gradle ./api/
+COPY ./models/src/main/ ./models/src/main/
+COPY ./models/build.gradle ./models/
+COPY ./services/src/main/ ./services/src/main/
+COPY ./services/build.gradle ./services/
+COPY ./build.gradle ./
+COPY ./gradle.properties ./
+COPY ./settings.gradle ./
+COPY ./gradle/libs.versions.toml ./gradle/
+RUN gradle build --no-daemon
+
+# ----------------------------------------------------------------------- #
+FROM alpine/java:21-jdk AS run
+
+RUN adduser --system appuser
+USER appuser
+
+COPY --from=builder --chown=appuser:appuser /api/build/libs/api-0.2.0-SNAPSHOT.jar app.jar
+
+EXPOSE 8400
+USER appuser
+
+CMD ["java", "-jar", "app.jar"]
+