Replace JS-based GitHub Actions (dtolnay/rust-toolchain, actions/setup-node) in the Linux job with shell commands that check if Rust and Node.js are already present before installing. All three jobs (Linux, macOS, Windows) now use the same pattern: skip installation if the tool is already available on the runner. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>