Add a marketing landing page for inputhalo.freno.me with a hero section
(theme-aware app icon, glitch title, tagline), feature highlights, and a
download section offering a macOS DMG via the tRPC signed-S3 URL endpoint
plus an App Store link.
Extract the download orchestration into a pure, side-effect-free helper
(query/performInputHaloDownload) so the asset-name and redirect contract is
unit-tested in isolation, mirroring the existing site-aware page-head /
nav-config split. Include dark and default app-icon exports in the public
folder.
