Bootstrapping a new machine

A checklist students can run top-to-bottom on a fresh laptop:

1. Install system updates and Xcode Command Line Tools (macOS) / build-essential (Linux)
2. Install Homebrew (or equivalent)
3. Install git, configure name/email, set up SSH keys
4. Install your version manager(s) and one default language version
5. Install your editor and sign in to sync settings
6. Clone a known-good project and verify the full setup works end-to-end