fix(identity-service): 移除所有中国镜像配置，使用官方源+代理

- 移除 Alpine 镜像加速
- 移除 Debian 镜像加速
- 移除 npm 镜像加速
- 通过 Docker 代理访问官方源

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

backend/services/identity-service/Dockerfile

@@ -5,12 +5,6 @@
 # Build stage - use Alpine for smaller build context
 FROM node:20-alpine AS builder
 
-# Use Aliyun mirror for Alpine packages (China acceleration)
-RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.aliyun.com/g' /etc/apk/repositories
-
-# Use taobao npm registry (China acceleration)
-RUN npm config set registry https://registry.npmmirror.com
-
 WORKDIR /app
 
 # Copy package files
@@ -41,19 +35,12 @@ FROM node:20-slim
 
 WORKDIR /app
 
-# Use Aliyun mirror for Debian packages (China acceleration)
-RUN sed -i 's/deb.debian.org/mirrors.aliyun.com/g' /etc/apt/sources.list.d/debian.sources 2>/dev/null || \
-    sed -i 's/deb.debian.org/mirrors.aliyun.com/g' /etc/apt/sources.list 2>/dev/null || true
-
 # Install OpenSSL and curl for health checks
 RUN apt-get update && apt-get install -y --no-install-recommends \
     openssl \
     curl \
     && rm -rf /var/lib/apt/lists/*
 
-# Use taobao npm registry (China acceleration)
-RUN npm config set registry https://registry.npmmirror.com
-
 # Install production dependencies only
 COPY package*.json ./
 RUN npm ci --only=production