openai/gpt-chat-latest → A (9:1)

Side A adds the missing GITHUB_API_BASE_URL configuration with a default value, preventing a runtime NameError in the GitHub OAuth callback and restoring functionality. Side B is almost entirely Clippy-driven cleanup and minor test adjustments (pattern simplifications, formatting, type alias, dead_code allowance, adding a missing #[test]) that improve code quality but do not materially change project behavior.