- configure Tailwind v4 via `@tailwindcss/vite` with a full CSS variable theme (light/dark) and Geist Variable font
- add shadcn `components.json` (base-lyra style, tabler icons) and scaffold `Button` component using `@base-ui/react`
- wire in `TanStackDevtools` + `TanStackRouterDevtoolsPanel` in the root layout
- switch path alias from `~/` to `@/` across tsconfig, routes, and components
- add `clsx`/`tailwind-merge` `cn` utility, `vitest`, `prettier-plugin-tailwindcss`, and other supporting deps