OpenAI 图片中转服务

OPENAI_API_KEY：已配置

健康检查：/health.php

可视化测试：/test.php

生成接口：POST /generate.php

curl -X POST "/generate.php" \
  -H "Content-Type: application/json" \
  -H "X-Proxy-Token: your-token" \
  -d '{"prompt":"一张企业商城促销海报，清爽高级，不要文字","width":1200,"height":420,"count":1}'