ci: Dockerfile 换国内源加速构建

- npm 用 npmmirror（淘宝源），go 用 goproxy.cn
- 大幅缩短 132 上 npm ci / go mod download 耗时

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Dockerfile

@@ -2,20 +2,21 @@
 FROM node:20-alpine AS web
 WORKDIR /app/web
 COPY web/package*.json ./
-RUN npm ci
+RUN npm config set registry https://registry.npmmirror.com && npm ci
 COPY web/ ./
 RUN npm run build
 
 FROM node:20-alpine AS admin
 WORKDIR /app/admin
 COPY admin/package*.json ./
-RUN npm ci
+RUN npm config set registry https://registry.npmmirror.com && npm ci
 COPY admin/ ./
 RUN npm run build
 
 # ── 2. 编译 Go（embed 两份前端产物）──
 FROM golang:1.26-alpine AS server
 WORKDIR /app/server
+ENV GOPROXY=https://goproxy.cn,direct
 COPY server/go.mod server/go.sum ./
 RUN go mod download
 COPY server/ ./