fix(clipboard): tessellate pasted ACIS solids so they render

Paste added the entities but never rebuilt the solid mesh caches, which are
only populated by populate_meshes_from_document (file open, undo, a few
commands). A pasted 3D solid — top-level or inside a recreated block
definition — therefore had no mesh and stayed invisible. Rebuild the mesh
caches after the paste so the solids show up.

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

src/app/cmd_result.rs

@@ -618,6 +618,10 @@ impl OpenCADStudio {
                     for h in new_handles {
                         self.tabs[i].scene.select_entity(h, false);
                     }
+                    // Tessellate any pasted ACIS solids — top-level ones and
+                    // those inside a recreated block definition — so they
+                    // render instead of staying invisible. (#135)
+                    self.tabs[i].scene.populate_meshes_from_document();
                     self.tabs[i].dirty = true;
                     self.refresh_properties();
                     self.command_line