feat: unify on single repo-root compose file for dev and prod

frontend/Dockerfile

@@ -1,13 +1,13 @@
-# Production image for the React UI (build + Vite preview; internal use).
+# Frontend image for dev and prod (single image).
+# Dev specifics arrive via devcontainer.json / compose env — never via this
+# file. DevDeps are included: `npm run dev` must work with zero steps.
 FROM node:22-slim
 
-WORKDIR /srv/frontend
-COPY package.json package-lock.json ./
-RUN npm ci
+WORKDIR /srv/kirche-einfach/frontend
+COPY package.json package-lock.json entrypoint.sh ./
+RUN npm ci && chmod +x entrypoint.sh
 COPY . ./
-RUN npm run build
 
-ENV VITE_API_PROXY_TARGET=http://app:8000
 EXPOSE 3000
 
-CMD ["npm", "run", "preview", "--", "--host", "0.0.0.0", "--port", "3000"]
+ENTRYPOINT ["./entrypoint.sh"]