工具路径为exe时默认显示exe自身图标

ToolItem新增IsExePath计算属性，ExePathToIconConverter通过Icon.ExtractAssociatedIcon提取exe图标并缓存，卡片模板图标区改为三层优先级：FontAwesome > exe图标 > 首字母

PersonalToolBox/Views/MainWindow.xaml.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Specialized;
 using System.ComponentModel;
 using System.Drawing;
@@ -229,3 +230,53 @@ public class StringToIconCharConverter : IValueConverter
     public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
         => throw new NotImplementedException();
 }
+
+/// <summary>
+/// string (exe路径) → ImageSource: 提取 .exe 文件自身图标，带缓存
+/// </summary>
+public class ExePathToIconConverter : IValueConverter
+{
+    private static readonly ConcurrentDictionary<string, ImageSource?> Cache = new();
+
+    public object? Convert(object value, Type targetType, object parameter, CultureInfo culture)
+    {
+        if (value is not string path || path.Length == 0)
+            return null;
+
+        if (!path.EndsWith(".exe", StringComparison.OrdinalIgnoreCase))
+            return null;
+
+        return Cache.GetOrAdd(path, key =>
+        {
+            try
+            {
+                if (!File.Exists(key))
+                    return null;
+
+                using var icon = System.Drawing.Icon.ExtractAssociatedIcon(key);
+                if (icon == null)
+                    return null;
+
+                using var bitmap = icon.ToBitmap();
+                using var ms = new MemoryStream();
+                bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
+                ms.Seek(0, SeekOrigin.Begin);
+
+                var image = new BitmapImage();
+                image.BeginInit();
+                image.CacheOption = BitmapCacheOption.OnLoad;
+                image.StreamSource = ms;
+                image.EndInit();
+                image.Freeze();
+                return image;
+            }
+            catch
+            {
+                return null;
+            }
+        });
+    }
+
+    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        => throw new NotImplementedException();
+}