VTK viewer: restore Surface after a point cloud forces Points mode

Loading a point cloud correctly locks the shared actor to Points
representation, but the surface-mesh branch of the LOAD_MESH handler never
reset it -- so navigating from a point cloud back to a surface mesh (e.g.
scrolling a batch) left the mesh stuck rendering as points until you manually
picked Surface in settings.

Fix: in the non-point-cloud branch, restore property.setRepresentation to the
user's chosen mode (currentSettings.representation, default Surface). Point
clouds still switch to Points; switching back now returns to the chosen mode.

javascript/viewer_vtk.html

@@ -384,6 +384,12 @@
                     const filteredPolyData = normalsFilter.getOutputData();
                     mapper.setInputData(filteredPolyData);
                     currentPolyData = filteredPolyData;  // Update reference for field visualization
+
+                    // Restore the user's chosen representation (default Surface).
+                    // A point cloud forces Points mode on the shared actor property;
+                    // without this, a surface mesh loaded right after a point cloud
+                    // would stay stuck rendering as points.
+                    property.setRepresentation(currentSettings.representation);
                 }
                 mapper.update();