feat: nKode React + TypeScript SPA scaffold
- React + Vite + Tailwind CSS v4 + React Router
- Keypad component: 10-digit pad with dot indicators, keyboard support, haptic feel
- Auth pages: Login (email → keypad), Signup (email → method → keypad/key)
- Home page: session info, practice keypad
- Admin dashboard: placeholder stats + user management
- Developer dashboard: OIDC client registration UI placeholder
- WASM client wrapper: lazy loads from /wasm/, falls back to mock client
- TypeScript type declarations for nkode-client-wasm package
- Dark mode with system preference detection
- Auth state management with localStorage persistence + auto-expiry
- Code splitting: lazy-loaded route pages (~236KB main bundle)
- Inter font, clean indigo/slate design system