Phase 7: 自定义图标系统 + 组合嵌套 + 删除功能 + UI 优化

- 安装 FontAwesome.Sharp v6.6.0，新增 Helpers/IconProvider.cs（190+ 图标，11 分类）
- ToolEditWindow/GroupEditWindow: 添加图标选择 ComboBox，按分类分组，带图标预览
- MainWindow 卡片模板: 使用 fa:IconBlock 渲染图标，IconCode 为空时回退首字母
- 组合角标从 emoji 改为 FontAwesome Cubes 图标，放置于卡片右上角
- ComboBox 样式修复: TextBlock→ContentPresenter，支持 ItemTemplate+DisplayMemberPath
- ComboBox 滚轮修复: CanContentScroll=False 解决分组模式下滑轮跳组问题
- 编辑弹窗: 所有输入控件添加 VerticalContentAlignment=Center
- 组合可包含其他组合: GetAncestorIds 递归排除自身及祖先防止循环引用
- ProcessExecutionService: 支持嵌套组合递归执行，visited 集合防死循环
- MainWindow 右键菜单新增删除功能，工具和组合均支持
- 移除侧边栏顶部个人工具箱标题文字
- 更新测试: 适配组合嵌套逻辑，新增祖先排除测试 (83/83 通过)

PersonalToolBox/ViewModels/GroupEditViewModel.cs

@@ -1,7 +1,9 @@
 using System.Collections.ObjectModel;
+using System.ComponentModel;
 using System.Linq;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
+using PersonalToolBox.Helpers;
 using PersonalToolBox.Models;
 using PersonalToolBox.Services;
 
@@ -30,6 +32,9 @@ public partial class GroupEditViewModel : ObservableObject
     [ObservableProperty]
     private Category? _selectedCategory;
 
+    [ObservableProperty]
+    private IconProvider.IconOption? _selectedIcon;
+
     /// <summary>
     /// 可供勾选的普通工具列表（IsGroup == false）
     /// </summary>
@@ -40,6 +45,11 @@ public partial class GroupEditViewModel : ObservableObject
     /// </summary>
     public ObservableCollection<Category> Categories { get; } = new();
 
+    /// <summary>
+    /// 按分类分组的可用图标列表
+    /// </summary>
+    public ListCollectionView AvailableIconsView { get; }
+
     public Action<bool?>? CloseAction { get; set; }
     public bool Saved { get; private set; }
 
@@ -51,12 +61,16 @@ public partial class GroupEditViewModel : ObservableObject
         _logService = logService;
         _editingGroup = groupToEdit;
 
+        AvailableIconsView = new ListCollectionView(IconProvider.AvailableIcons);
+        AvailableIconsView.GroupDescriptions.Add(new PropertyGroupDescription("Category"));
+
         foreach (var cat in _dataService.Config.Categories)
             Categories.Add(cat);
 
-        // 加载所有普通工具（非组合）
+        // 加载所有工具（排除自身及祖先组合，防止循环引用）
+        var excludeIds = GetAncestorIds();
         var selectedIds = _editingGroup?.SubToolIds ?? new List<string>();
-        foreach (var tool in _dataService.Config.Tools.Where(t => !t.IsGroup))
+        foreach (var tool in _dataService.Config.Tools.Where(t => !excludeIds.Contains(t.Id)))
         {
             AvailableTools.Add(new SelectableTool
             {
@@ -71,6 +85,11 @@ public partial class GroupEditViewModel : ObservableObject
             Name = groupToEdit.Name;
             HotKey = groupToEdit.HotKey;
             SelectedCategory = Categories.FirstOrDefault(c => c.Id == groupToEdit.CategoryId);
+
+            if (!string.IsNullOrEmpty(groupToEdit.IconCode))
+            {
+                SelectedIcon = IconProvider.AvailableIcons.FirstOrDefault(i => i.Icon.ToString() == groupToEdit.IconCode);
+            }
         }
     }
 
@@ -95,6 +114,7 @@ public partial class GroupEditViewModel : ObservableObject
             if (_editingGroup != null)
             {
                 _editingGroup.Name = Name.Trim();
+                _editingGroup.IconCode = SelectedIcon?.Icon.ToString() ?? string.Empty;
                 _editingGroup.HotKey = HotKey.Trim();
                 _editingGroup.CategoryId = SelectedCategory?.Id ?? string.Empty;
                 _editingGroup.SubToolIds = selectedIds;
@@ -106,6 +126,7 @@ public partial class GroupEditViewModel : ObservableObject
                 _dataService.Config.Tools.Add(new ToolItem
                 {
                     Name = Name.Trim(),
+                    IconCode = SelectedIcon?.Icon.ToString() ?? string.Empty,
                     HotKey = HotKey.Trim(),
                     CategoryId = SelectedCategory?.Id ?? string.Empty,
                     IsGroup = true,
@@ -130,6 +151,31 @@ public partial class GroupEditViewModel : ObservableObject
     {
         CloseAction?.Invoke(false);
     }
+
+    /// <summary>
+    /// 获取需要排除的工具 ID 集合（自身 + 所有祖先组合），防止循环引用
+    /// </summary>
+    private System.Collections.Generic.HashSet<string> GetAncestorIds()
+    {
+        var ancestors = new System.Collections.Generic.HashSet<string>();
+        if (_editingGroup != null)
+        {
+            ancestors.Add(_editingGroup.Id);
+            CollectAncestors(_editingGroup.Id, ancestors);
+        }
+        return ancestors;
+    }
+
+    private void CollectAncestors(string groupId, System.Collections.Generic.HashSet<string> ancestors)
+    {
+        foreach (var tool in _dataService.Config.Tools.Where(t => t.IsGroup))
+        {
+            if (tool.SubToolIds.Contains(groupId) && ancestors.Add(tool.Id))
+            {
+                CollectAncestors(tool.Id, ancestors);
+            }
+        }
+    }
 }
 
 /// <summary>