~x-ai/grok-latest → A (2:1)

A adds a full CD workflow (checkout, flyctl setup, remote deploy with concurrency and secrets) that continuously keeps the Fly app in sync—lasting operational infrastructure. B is a necessary but narrow fix: deleting a 3-line rust-toolchain.toml that fought dtolnay’s CI toolchain and broke musl, with local pinning moved to mise; valuable correctness, smaller permanent surface.