feat: 完善 PortProxy 图形化管理工具

PortProxyTool.Wpf/Converters/NullableUnknownToStringConverter.cs

@@ -0,0 +1,17 @@
+using System.Globalization;
+using System.Windows.Data;
+
+namespace PortProxyTool.Wpf.Converters;
+
+public class NullableUnknownToStringConverter : IValueConverter
+{
+    public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        return value == null ? "未知" : value.ToString();
+    }
+
+    public object ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        throw new NotImplementedException();
+    }
+}