新增可解锁Hold机制并补全特殊强化提示

src/include/Tetris.h

@@ -49,6 +49,7 @@ struct PlayerStats
     int expUpgradeLevel;
     int previewUpgradeLevel;
     int lastChanceUpgradeLevel;
+    int holdUnlocked;
 };
 
 struct UpgradeOption
@@ -119,6 +120,8 @@ extern int currentScreen;
 extern int currentMode;
 extern int currentFallInterval;
 extern int nextTypes[3];
+extern int holdType;
+extern bool holdUsedThisTurn;
 extern int bricks[7][4][4][4];
 extern COLORREF BrickColor[7];
 
@@ -140,5 +143,6 @@ void ReturnToMainMenu();
 void OpenRulesScreen();
 void OpenUpgradeMenu();
 void ConfirmUpgradeSelection();
+void HoldCurrentPiece();
 
 void TDrawScreen(HDC hdc, HWND hWnd);