Add TanStack Start, sharing UI, settings, and deployment infra
Migrate from Vite SPA to TanStack Start for SSR on public routes with
per-route SEO meta tags. Add sharing UI with grant create/list/revoke,
settings page with AppView URL config, user menu with avatar and portal
dropdown, and Containerfiles for appview and web. Fix auth guards across
all device routes to read from Zustand store instead of dead router context.