fix: show concatenated path names as dialog filename for multi-select export

- Single: path name as default filename (unchanged)
- Multi: semicolon-separated names as hint, each file still saved individually

src/UI/WPF/ViewModels/PathEditingViewModel.cs

@@ -5965,7 +5965,9 @@ namespace NavisworksTransport.UI.WPF.ViewModels
                             : $"导出 {selectedRoutes.Count} 个路径",
                         Filter = "XML文件 (*.xml)|*.xml|JSON文件 (*.json)|*.json|CSV文件 (*.csv)|*.csv|DELMIA Apriso XML (*.aprxml)|*.aprxml|所有文件 (*.*)|*.*",
                         FilterIndex = 1,
-                        FileName = selectedRoutes.Count == 1 ? firstRoute.Name?.Replace(" ", "_") ?? "路径" : "路径",
+                        FileName = selectedRoutes.Count == 1
+                            ? firstRoute.Name?.Replace(" ", "_") ?? "路径"
+                            : string.Join("; ", selectedRoutes.Select(r => r.Name.Replace(" ", "_"))),
                         DefaultExt = "xml",
                         AddExtension = true
                     };