updated dockerfile for frontend

Dockerfile

@@ -1,17 +1,16 @@
-FROM mirror.gcr.io/library/node:20-bullseye-slim
-
+# Stage 1: Build
+FROM mirror.gcr.io/library/node:20-bullseye-slim AS builder
 WORKDIR /app
-
 COPY package*.json ./
-RUN npm install
-
+RUN npm ci
 COPY . .
-
 ARG VITE_API_BASE_URL
 ENV VITE_API_BASE_URL=$VITE_API_BASE_URL
-
 RUN npm run build
 
-EXPOSE 5173
-
-CMD ["npm", "run", "preview"]
+# Stage 2: Serve with nginx (tiny ~50MB vs ~500MB)
+FROM nginx:alpine AS production
+COPY --from=builder /app/dist /usr/share/nginx/html
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+EXPOSE 80
+CMD ["nginx", "-g", "daemon off;"]