Launch ScientFactory website and desktop downloads

[yaacovcorcos]

Summary

• launches the production ScientFactory marketing site and responsive download page
• adds compact macOS Apple Silicon / Intel selection plus direct Windows and Linux downloads
• adds a validated Cloudflare Pages release endpoint with cache and failure handling
• hardens the cross-platform GitHub Release workflow with exact asset validation and SHA-256 checksums

Validation

• full workspace tests: 12 tasks passed (1,884 CLI tests plus all other packages)
• full workspace typecheck: 9/9 packages passed
• marketing release tests: 9 passed
• edge function tests: 4 passed
• production marketing and Pages Function builds passed
• format, lint (0 errors), immutable action, brand, and release-smoke checks passed

Release note

The first public installers remain explicitly labeled early access and may be unsigned.