fix(viewport): show new paper-space viewport border without a zoom

Creating a viewport in a layout commits through document.add_entity_to_layout
+ Scene::auto_fit_viewport, both of which skip the geometry-cache bump that
Scene::add_entity performs for every other entity. So the new viewport's
border wasn't tessellated until the next zoom/pan happened to invalidate the
cache. Bump the wire tessellation (no-blocks: a viewport touches no block
definitions) right after the viewport is added.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/properties.rs

@@ -687,6 +687,12 @@ impl OpenCADStudio {
             {
                 Ok(new_handle) => {
                     self.tabs[i].scene.auto_fit_viewport(new_handle);
+                    // Adding a viewport straight onto the document layout
+                    // bypasses Scene::add_entity, which is what normally
+                    // invalidates the wire-tessellation cache. Without this the
+                    // new viewport's border isn't tessellated until the next
+                    // zoom/pan forces a rebuild.
+                    self.tabs[i].scene.bump_geometry_no_blocks();
                     Some(new_handle)
                 }
                 Err(e) => {