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.test.tsx

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+import { render, screen } from "@testing-library/react";
+import { App } from "./app";
+
+test("renders the app placeholder", () => {
+  render(<App />);
+  expect(screen.getByRole("heading", { name: /collection/i })).toBeInTheDocument();
+});

web/src/app.tsx

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+export function App() {
+  return <h1>Collection</h1>;
+}

web/src/main.tsx

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+import { StrictMode } from "react";
+import { createRoot } from "react-dom/client";
+import { App } from "./app";
+
+createRoot(document.getElementById("root")!).render(
+  <StrictMode>
+    <App />
+  </StrictMode>,
+);

web/src/test/setup.ts

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+import "@testing-library/jest-dom/vitest";

web/src/vite-env.d.ts

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+/// <reference types="vite/client" />