feat(web): scaffold Vite + React + TS SPA with Vitest

Bootstraps the web/ SPA: Vite 6 + React 19 + TypeScript 5.8, Vitest
with jsdom, @testing-library/react, and a green smoke test asserting
the App renders its Collection heading.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/src/app.tsx

@@ -0,0 +1,3 @@
+export function App() {
+  return <h1>Collection</h1>;
+}