fix: 优化镜像源，提升速度

frontend/Dockerfile

@@ -1,15 +1,17 @@
-FROM docker.m.daocloud.io/library/node:22-alpine AS builder
+# 基础镜像来自 Docker Hub；请在本机配置阿里云镜像加速器后再构建（见仓库 docker-compose.yml 注释）
+FROM node:22-alpine AS builder
 
 WORKDIR /app
 
 RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.aliyun.com/g' /etc/apk/repositories
 COPY package.json /app/package.json
+# 阿里云镜像站指定的 npm 同步源（原淘宝镜像域名已迁移至 npmmirror）
 RUN npm config set registry https://registry.npmmirror.com && npm install
 
 COPY . /app
 RUN npm run build
 
-FROM docker.m.daocloud.io/library/nginx:1.27-alpine
+FROM nginx:1.27-alpine
 RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.aliyun.com/g' /etc/apk/repositories
 COPY nginx.conf /etc/nginx/conf.d/default.conf
 COPY --from=builder /app/dist /usr/share/nginx/html