refactor(FN-1242): migrate desktop vitest config to project-based setup

- Replace environmentMatchGlobs with explicit Vitest test.projects entries for desktop and desktop-renderer suites
- Keep desktop core tests on the threads pool and renderer tests in a jsdom-targeted project
- Increase the batch-import 429 retry test timeout from 30s to 60s to reduce CI flakiness

packages/dashboard/src/routes.test.ts

@@ -4143,7 +4143,7 @@ describe("POST /github/issues/batch-import", () => {
     expect(res.body.results[0].error).toContain("rate limit");
     expect(res.body.results[0].retryAfter).toBe(1);
     expect(fetchSpy.mock.calls.length).toBeGreaterThanOrEqual(4);
-  }, 30000); // Retry path can exceed 15s in CI/load-constrained environments
+  }, 60000); // Retry path can exceed 30s in CI/load-constrained environments
 
   it("processes issues sequentially (not parallel)", async () => {
     vi.useFakeTimers();