工作区保存参数增加浏览路径

SpineViewer/Models/WorkspaceModel.cs

@@ -12,6 +12,7 @@ namespace SpineViewer.Models
 {
     public class WorkspaceModel
     {
+        public string? ExploringDirectory { get; set; }
         public RendererWorkspaceConfigModel RendererConfig { get; set; } = new();
         public List<SpineObjectWorkspaceConfigModel> LoadedSpineObjects { get; set; } = [];
     }