feat: add gateway-service (Spring Cloud Gateway + Consul)

gateway-service/docker/Dockerfile

@@ -0,0 +1,25 @@
+# --- Build stage ---
+FROM maven:3.9.9-eclipse-temurin-24-alpine AS build
+WORKDIR /app
+COPY pom.xml .
+RUN mvn dependency:go-offline -B
+COPY src ./src
+RUN mvn clean package -DskipTests -B
+
+# --- Runtime stage ---
+FROM eclipse-temurin:25-jre-alpine
+WORKDIR /app
+
+RUN addgroup -S appgroup && adduser -S appuser -G appgroup
+
+COPY --from=build /app/target/*.jar app.jar
+
+RUN chown -R appuser:appgroup /app
+USER appuser
+
+EXPOSE 8080
+
+HEALTHCHECK --interval=30s --timeout=5s --retries=3 \
+  CMD wget -qO- http://localhost:8080/actuator/health || exit 1
+
+ENTRYPOINT ["java", "-jar", "app.jar", "--spring.profiles.active=prod"]