Build a Memory Game in React.

Requirements:

1. Display a grid of cards (e.g., 4x4) face-down.
2. Each card has a matching pair.
3. Players can flip two cards at a time.
4. If the flipped cards match, keep them face-up; otherwise, flip them back after a short delay.
5. Track the number of moves or attempts.
6. End the game when all pairs are matched.
7. Focus on functionality over styling.