Added Dockerfile and dockerignore

.dockerignore

@@ -0,0 +1,7 @@
+node_modules
+js/node_modules
+target
+.git
+.DS_Store
+dist
+js/dist

infra/Dockerfile

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+# Build the React frontend
+FROM mirror.gcr.io/library/node:20 AS frontend-build
+
+WORKDIR /js
+COPY js/package.json js/pnpm-lock.yaml ./
+RUN corepack enable pnpm && pnpm i --frozen-lockfile
+
+COPY js/ ./
+RUN pnpm run build
+
+# Build the Spring Boot backend and package the frontend into the app
+FROM mirror.gcr.io/library/eclipse-temurin:25-jdk-jammy AS backend-build
+
+WORKDIR /app
+COPY mvnw pom.xml ./
+COPY .mvn/ .mvn/
+RUN ./mvnw dependency:resolve -B
+
+COPY src ./src
+COPY --from=frontend-build /js/dist/ src/main/resources/static/
+RUN ./mvnw package -B -DskipTests
+
+# Create the final runtime image
+FROM mirror.gcr.io/library/eclipse-temurin:25-jre-jammy
+
+RUN groupadd --system spring \
+    && useradd --system --gid spring --home-dir /app spring \
+    && mkdir -p /app \
+    && chown spring:spring /app
+
+WORKDIR /app
+
+COPY --from=backend-build --chown=spring:spring /app/target/*.jar app.jar
+
+ARG SERVER_PROFILES=prod
+ENV SPRING_PROFILES_ACTIVE=${SERVER_PROFILES}
+
+USER spring:spring
+
+EXPOSE 8080
+ENTRYPOINT ["java", "-jar", "app.jar"]