Download page variants

Four thin directions. Pick the one that feels sharpest, then we promote it to the root page.

Closest to the current legal site. Quiet, direct, very little ceremony.

Adds QR codes for App Store and Google Play on larger screens, then collapses back to links on mobile.

More explicit about the full platform roadmap, including Windows and Linux coming soon.

QR-first mobile installs, then full-width web and macOS cells. Windows is removed.