chore: retire demo technical debt

frontend/Dockerfile

@@ -1,5 +1,5 @@
 # Build Stage
-FROM node:18-alpine as build-stage
+FROM node:18-alpine AS build-stage
 
 WORKDIR /app
 
@@ -10,7 +10,7 @@ COPY . .
 RUN npm run build
 
 # Production Stage
-FROM nginx:alpine as production-stage
+FROM nginx:alpine AS production-stage
 
 # 复制构建产物到 Nginx
 COPY --from=build-stage /app/dist /usr/share/nginx/html