Use `vitest` for backend tests: - `bench` script now uses [vitest's `bench`](https://vitest.dev/api/#bench) - e2e test fails with same error happening now with jest:`data-testid` attribute not present. vitest left, jest right <img width="1264" height="603" alt="image" src="https://github.com/user-attachments/assets/56fc43a6-e143-4208-bf14-7e016aae7fa9" />