v0.0.1-beta.4

New:

• Add OPENAI_MODEL env.

Example:

# OpenAI
OPENAI_BASE_URL=https://api.openai.com/v1
OPENAI_API_KEY=xxx
OPENAI_MODEL=gpt-5

# DeepSeek
OPENAI_BASE_URL=https://api.deepseek.com
OPENAI_API_KEY=xxx
OPENAI_MODEL=deepseek-chat

# Or other OpenAI API compatible services.