优化更新代码，添加界面功能并整合

WPFluent/Converters/TreeModelCanExpandConverter.cs

@@ -0,0 +1,22 @@
+using System;
+using System.Globalization;
+using System.Windows;
+using System.Windows.Data;
+
+namespace WPFluent.Converters;
+
+[ValueConversion(typeof(bool), typeof(Visibility))]
+internal sealed class TreeModelCanExpandConverter : IValueConverter
+{
+    public bool IsInverted { get; set; } = false;
+
+    public object Convert(object o, Type type, object parameter, CultureInfo culture)
+    {
+        return (bool)o ^ IsInverted ? Visibility.Visible : Visibility.Hidden;
+    }
+
+    public object ConvertBack(object o, Type type, object parameter, CultureInfo culture)
+    {
+        throw new NotSupportedException();
+    }
+}