Add Docker mirror configuration and build scripts

Co-authored-by: Cursor <cursoragent@cursor.com>

deploy/docker/admin.Dockerfile

@@ -1,6 +1,8 @@
 # 生产环境 Admin Dockerfile（最小构建）
 # 用途：构建优化的 Next.js 生产镜像
-FROM node:20-alpine AS builder
+# 支持通过构建参数指定基础镜像
+ARG NODE_IMAGE=node:20-alpine
+FROM ${NODE_IMAGE} AS builder
 
 WORKDIR /app
 
@@ -22,7 +24,8 @@ ENV NEXT_TELEMETRY_DISABLED=1
 RUN npm run build
 
 # 生产镜像
-FROM node:20-alpine
+ARG NODE_IMAGE=node:20-alpine
+FROM ${NODE_IMAGE}
 
 WORKDIR /app