improve:PPT联动及墨迹管理

改回原处理模式，优化翻页操作

Ink Canvas/MainWindow_cs/MW_Save&OpenStrokes.cs

@@ -79,7 +79,7 @@ namespace Ink_Canvas
 
                         for (int i = 1; i <= totalSlides; i++)
                         {
-                            var slideStrokes = _multiPPTInkManager?.LoadSlideStrokes(i);
+                            var slideStrokes = _singlePPTInkManager?.LoadSlideStrokes(i);
                             if (slideStrokes != null && slideStrokes.Count > 0)
                             {
                                 allPageStrokes.Add(slideStrokes);
@@ -581,7 +581,7 @@ namespace Ink_Canvas
                 timeMachine.ClearStrokeHistory();
 
                 // 重置PPT墨迹存储
-                _multiPPTInkManager?.ClearAllStrokes();
+                _singlePPTInkManager?.ClearAllStrokes();
 
                 // 读取所有页面的墨迹文件
                 var files = Directory.GetFiles(tempDir, "page_*.icstk");
@@ -595,7 +595,7 @@ namespace Ink_Canvas
                             var strokes = new StrokeCollection(fs);
                             if (strokes.Count > 0)
                             {
-                                _multiPPTInkManager?.ForceSaveSlideStrokes(pageNumber, strokes);
+                                _singlePPTInkManager?.ForceSaveSlideStrokes(pageNumber, strokes);
                             }
                         }
                     }
@@ -605,7 +605,7 @@ namespace Ink_Canvas
                 if (_pptManager?.IsInSlideShow == true)
                 {
                     int currentSlide = _pptManager.GetCurrentSlideNumber();
-                    var currentStrokes = _multiPPTInkManager?.LoadSlideStrokes(currentSlide);
+                    var currentStrokes = _singlePPTInkManager?.LoadSlideStrokes(currentSlide);
                     if (currentStrokes != null && currentStrokes.Count > 0)
                     {
                         inkCanvas.Strokes.Add(currentStrokes);