optimize Dockerfile and update nginx base image

Dockerfile

@@ -1,11 +1,8 @@
 # Build stage
 FROM node:20-alpine AS builder
-
 WORKDIR /app
-
 COPY package*.json ./
 RUN npm ci
-
 COPY . .
 
 # Build without type checking (vite build only)
@@ -15,18 +12,10 @@ ENV SIMPLE_MODE=$SIMPLE_MODE
 RUN npm run build -- --mode production
 
 # Production stage
-FROM nginxinc/nginx-unprivileged:1.29-alpine
+FROM nginxinc/nginx-unprivileged:stable-alpine-slim
 
-# Copy files as root first, then change ownership
-COPY --from=builder /app/dist /usr/share/nginx/html
-COPY nginx.conf /etc/nginx/nginx.conf
-
-# Change ownership while still root, then switch to nginx user
-USER root
-RUN mkdir -p /etc/nginx/tmp && \
-    chown -R nginx:nginx /usr/share/nginx/html /etc/nginx/tmp
-USER nginx
-
-EXPOSE 8080
+COPY --chown=nginx:nginx --from=builder /app/dist /usr/share/nginx/html
+COPY --chown=nginx:nginx nginx.conf /etc/nginx/nginx.conf
+RUN mkdir -p /etc/nginx/tmp && chown -R nginx:nginx /etc/nginx/tmp
 
 CMD ["nginx", "-g", "daemon off;"]