openai/gpt-5.2-chat → B (9:1)

Commit B performs a workspace-wide rustfmt run affecting many source files, improves code consistency, pins rustfmt and clippy in rust-toolchain.toml to stabilize tooling, adds VS Code configuration for correct rust-analyzer toolchain usage, and fixes/cleans related code and CSS. This impacts a large portion of the codebase and developer workflow. Commit A is a small UI/CSS tweak and removal of some markup/functions labeled as 'nits', with limited scope. Therefore B contributes substantially more overall.