openai/gpt-5.3-chat → A (9:1)

Commit A makes widespread improvements across the codebase: workspace-wide formatting, tooling fixes (rustfmt/clippy pinning), editor configuration, minor CSS cleanup, and consistent code style updates in many files. While mostly non-functional, it meaningfully improves maintainability and developer experience. Commit B only removes a single test, which is a very minor change with negligible impact.