fix(identity-service): 添加 CA 证书以支持 HTTPS 连接

- 在 Dockerfile 中安装 ca-certificates 包
- 修复阿里云短信 API SSL 证书验证错误
- 解决 "error setting certificate file" 问题

问题: curl 提示 "error setting certificate file: /etc/ssl/certs/ca-certificates.crt"
原因: 容器内缺少 CA 证书文件
解决: 安装 ca-certificates 包

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

backend/services/identity-service/Dockerfile

@@ -35,9 +35,10 @@ FROM node:20-slim
 
 WORKDIR /app
 
-# Install OpenSSL and curl for health checks
+# Install OpenSSL, CA certificates, and curl for health checks
 RUN apt-get update && apt-get install -y --no-install-recommends \
     openssl \
+    ca-certificates \
     curl \
     && rm -rf /var/lib/apt/lists/*