improve:墨迹保存

Ink Canvas/MainWindow_cs/MW_Screenshot.cs

@@ -102,21 +102,13 @@ namespace Ink_Canvas {
             }
             catch (Exception ex) when 
                 (ex is IOException || 
-                 ex is UnauthorizedAccessException) // 明确捕获与目录创建相关的异常
+                 ex is UnauthorizedAccessException)
             {
-                // 如果创建失败则尝试使用文档目录
-                basePath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
+                // 如果创建失败则使用软件根目录作为最终备选
+                basePath = AppDomain.CurrentDomain.BaseDirectory;
                 fullPath = Path.Combine(basePath, "Auto Saved - Screenshots", dateFolder);
-
-                try {
-                    Directory.CreateDirectory(fullPath);
-                }
-                catch (Exception) {
-                    // 如果文档目录也不可用，则使用软件根目录
-                    basePath = AppDomain.CurrentDomain.BaseDirectory;
-                    fullPath = Path.Combine(basePath, "Auto Saved - Screenshots", dateFolder);
-                    Directory.CreateDirectory(fullPath);
-                }
+                
+                Directory.CreateDirectory(fullPath);
             }
             
             return Path.Combine(fullPath, $"{fileName}.png");