Introduce a working v0 Nebula Shell prototype (Tauri frontend) and redesign docs. Adds a complete frontend under src/ (views: home, lock, library, settings, overlays), core adapters (input, nav, passkey, router, state), global styles and shell guidelines, and view-specific HTML/CSS/JS. Update README with prototype notes, install/run/build instructions and controller testing tips. Update package.json to add dev/build scripts and add @nebulaproject/core as a dependency. Also include a detailed REDESIGN_DOCUMENTATION.md describing the Xbox-inspired horizontal dashboard, component patterns, and developer notes.
