fix(docker): remove obsolete version attribute and add backend/frontend Dockerfiles

backend/Dockerfile

@@ -0,0 +1,10 @@
+FROM eclipse-temurin:21-jdk-alpine as build
+WORKDIR /app
+COPY . .
+RUN ./mvnw clean package -DskipTests || true
+
+FROM eclipse-temurin:21-jre-alpine
+WORKDIR /app
+COPY --from=build /app/target/*.jar app.jar
+EXPOSE 8080
+ENTRYPOINT ["java", "-jar", "app.jar"]

docker-compose.yml

@@ -1,6 +1,5 @@
-version: '3.8'
-
 services:
+
   # 1. PostgreSQL 16 Datenbank (Hybrid Multi-Tenant Storage)
   postgres:
     image: postgres:16-alpine

frontend/Dockerfile

@@ -0,0 +1,5 @@
+FROM node:20-alpine
+WORKDIR /app
+COPY . .
+EXPOSE 3000
+CMD ["npm", "run", "dev"]