test(web): MSW harness with typed handlers, fixtures, and client tests

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

web/src/test/setup.ts

@@ -1 +1,11 @@
 import "@testing-library/jest-dom/vitest";
+import { afterAll, afterEach } from "vitest";
+
+import { server } from "./server";
+
+// Start MSW at module level so its fetch patch is in place before any test
+// module captures globalThis.fetch via openapi-fetch's createClient().
+server.listen({ onUnhandledRequest: "error" });
+
+afterEach(() => server.resetHandlers());
+afterAll(() => server.close());