PORT=3000
MONGODB_URI=mongodb://localhost:27017/multi_llm_chat
OPENAI_API_KEY=your_openai_key_here
# 可选：自定义 OpenAI Base
OPENAI_BASE_URL=https://api.openai.com

# DeepSeek 兼容 (同 OpenAI 协议)
DEEPSEEK_API_KEY=your_deepseek_key_here
DEEPSEEK_BASE_URL=https://api.deepseek.com