Build Faust personal gallery

[lurui1997]

Summary

• reorganize Faust into an isolated mixed-stack project gallery with preserved notes
• add strict metadata validation, safe project scaffolding, deterministic gallery generation, and maintenance commands
• add an accessible editorial Astro site with shareable filters and GitHub Pages deployment

Verification

• pnpm install --frozen-lockfile
• pnpm check (232 tests, zero Astro diagnostics)
• blank/web/script templates verified in an isolated repository
• desktop/mobile, keyboard, focus, filters, covers, links, XSS omission, and reduced-motion acceptance matrix passed
• GitHub Pages workflow uses least privilege and immutable action SHAs