🔄 Refactored animation systems to use UniTask instead of Coroutine
- ButtonScaler rewritten using async UniTaskVoid with CancellationTokenSource
- ItemEffecter and ItemAnimator converted to UniTask (fully cancellable)
- Removed StartCoroutine / StopCoroutine usage
- Improved readability, safety, and lifecycle management
🧪 Behavior fully preserved — no functional changes