代码优化：简化命名空间引用，使用using别名

修改内容：
- 将 Autodesk.Navisworks.Api.Progress 简化为 Progress
- 将 Autodesk.Navisworks.Api.Application.BeginProgress() 简化为 NavisApplication.BeginProgress()
- 将 Autodesk.Navisworks.Api.Application.EndProgress() 简化为 NavisApplication.EndProgress()

理由：
- 文件顶部已经有 using Autodesk.Navisworks.Api;
- 文件顶部已经有 using NavisApplication = Autodesk.Navisworks.Api.Application;
- 使用using别名可以简化代码，提高可读性

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/UI/WPF/ViewModels/LayerManagementViewModel.cs

@@ -1425,7 +1425,7 @@ namespace NavisworksTransport.UI.WPF.ViewModels
             List<ModelSplitterManager.SplitPreviewResult> previewResultsForSave,
             CancellationToken cancellationToken)
         {
-            Autodesk.Navisworks.Api.Progress progress = null;
+            Progress progress = null;
             try
             {
                 // 确保输出目录存在
@@ -1441,7 +1441,7 @@ namespace NavisworksTransport.UI.WPF.ViewModels
                 // 🎯 创建批量导出进度条（在主线程中）
                 await System.Windows.Application.Current.Dispatcher.InvokeAsync(() =>
                 {
-                    progress = Autodesk.Navisworks.Api.Application.BeginProgress("批量导出分层",
+                    progress = NavisApplication.BeginProgress("批量导出分层",
                         $"准备导出 {previewResultsForSave.Count} 个分层...");
                 });
 
@@ -1460,8 +1460,8 @@ namespace NavisworksTransport.UI.WPF.ViewModels
                             progress.Update(currentProgress);
 
                             // 更新进度条描述
-                            Autodesk.Navisworks.Api.Application.EndProgress();
-                            progress = Autodesk.Navisworks.Api.Application.BeginProgress("批量导出分层",
+                            NavisApplication.EndProgress();
+                            progress = NavisApplication.BeginProgress("批量导出分层",
                                 $"正在导出第 {i + 1}/{previewResultsForSave.Count} 个分层：{preview.LayerName}");
                         }
                         else if (progress != null && progress.IsCanceled)
@@ -1532,7 +1532,7 @@ namespace NavisworksTransport.UI.WPF.ViewModels
                     {
                         try
                         {
-                            Autodesk.Navisworks.Api.Application.EndProgress();
+                            NavisApplication.EndProgress();
                             LogManager.Info("[LayerManagementViewModel] 批量导出进度条已关闭");
                         }
                         catch (Exception progressEx)