fix: Dockerfile 基础镜像改为国内 DaoCloud 镜像源，修复构建失败

Dockerfile

@@ -1,7 +1,8 @@
 # ==========================================
 # 1. Build Stage
 # ==========================================
-FROM node:22-alpine AS builder
+# 使用国内可访问的 DaoCloud 镜像源（Docker Hub 在国内不可达）
+FROM docker.m.daocloud.io/library/node:22-alpine AS builder
 
 # 启用 corepack 并安装 pnpm
 RUN corepack enable && corepack prepare pnpm@9 --activate
@@ -24,7 +25,7 @@ RUN pnpm run build
 # ==========================================
 # 2. Production Stage
 # ==========================================
-FROM node:22-alpine AS runner
+FROM docker.m.daocloud.io/library/node:22-alpine AS runner
 
 # 设置工作目录
 WORKDIR /app