* fix: add custom anthropic baseURL
* feat: add baseURL support for all AI providers
- Add GOOGLE_BASE_URL for Google Generative AI
- Add AZURE_BASE_URL for Azure OpenAI
- Add OLLAMA_BASE_URL support (was documented but not implemented)
- Add OPENROUTER_BASE_URL for OpenRouter
- Fix missing semicolon in Anthropic case
- Update env.example with new environment variables
Closes#20
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Co-authored-by: dayuan.jiang <jdy.toh@gmail.com>
