refactor: enhance GameStateStore integration and improve skill management

scripts/UI/GameOverScreen.cs

@@ -11,29 +11,26 @@ public partial class GameOverScreen : Control
     [Export] public Button MainMenuButton { get; set; }
     [Export] public PackedScene MainMenuScene { get; set; }
 
-    private GameManager _gameManager;
-
     public override void _Ready()
     {
-        _gameManager = GameManager.Instance;
         RestartButton.Pressed += OnRestartClicked;
         MainMenuButton.Pressed += OnMainMenuClicked;
     }
 
     private void OnMainMenuClicked()
     {
-        _gameManager.ResetPlayerState();
+        GameStateStore.Instance?.ResetAll();
         GetTree().ChangeSceneToPacked(MainMenuScene);
     }
 
     private void OnRestartClicked()
     {
-        _gameManager.RestartGame();
+        GameManager.Instance?.RestartGame();
     }
 
     public void OnPlayerDeath()
     {
-        if (_gameManager == null || _gameManager.GetLives() != 0) return;
+        if (GameStateStore.Instance?.Player.Lives != 0) return;
 
         GameOverPanel.Show();
     }