Initial testing framework

vitest.setup.ts

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+import "@testing-library/jest-dom/vitest";
+import { afterAll, afterEach, beforeAll } from "vitest";
+import { server } from "./tests/msw/server";
+// expose Tailwind tokens to JSDOM (for design token checks)
+import "./app/tailwind.css";
+
+// MSW for API integration tests (mock fetch)
+beforeAll(() => server.listen({ onUnhandledRequest: "bypass" }));
+afterEach(() => server.resetHandlers());
+afterAll(() => server.close());