fix: clear all IsSelected flags after export to prevent stale selections

- Added finally block to reset IsSelected on all PathRoutes
- Prevents multi-select state from leaking into subsequent single exports

src/UI/WPF/ViewModels/PathEditingViewModel.cs

@@ -6038,6 +6038,12 @@ namespace NavisworksTransport.UI.WPF.ViewModels
                     LogManager.Error($"导出路径异常: {ex.Message}", ex);
                     UpdateMainStatus($"❌ 导出异常: {ex.Message}");
                 }
+                finally
+                {
+                    // 清除所有选中状态，避免下次导出残留
+                    foreach (var r in PathRoutes)
+                        r.IsSelected = false;
+                }
             }, "导出路径");
         }