Implemented `requestAnimationFrame` throttling for the scroll event listener in `Navbar` to reduce the frequency of state updates and logic execution.
- Wrapped scroll handler in `requestAnimationFrame`.
- Added performance test `src/components/layout/Navbar.test.tsx` verifying logic runs once per frame instead of per event.
- Verified functional correctness of scroll state updates.
- Fixed `useTypingEffect` test environment.
