feat(modify): commercial solutions keyword options for MOVE, COPY, FILLET, CHAMFER, OFFSET

MOVE: Displacement, Enter at the second point uses the base as the vector.
COPY: Displacement, mOde (Single/Multiple), Undo of the last copy.
FILLET: Undo of the last fillet (the command refreshes its entity cache
through the new CadCommand::on_document_undone hook after the host undoes
the document step). CHAMFER: Multiple and Undo. OFFSET: Erase (the offset
replaces its source), Layer (Current/Source), Undo, Exit.
POLY3D, TRACE, MIRROR and MEASUREGEOM expose the keywords they already
accepted as options, so the context menu and option buttons list them.

The pinned prompt now keeps informational bracket groups such as
"[3 objects]" and only drops real option listings when the buttons take over.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/app/command_driver.rs

@@ -6599,6 +6599,12 @@ impl OpenCADStudio {
                         }
                     }
                 }
+                {
+                    let tab = &mut self.tabs[i];
+                    if let Some(command) = tab.active_cmd.as_mut() {
+                        command.on_document_undone(&tab.scene.document);
+                    }
+                }
                 let prompt = self.tabs[i].active_cmd.as_ref().map(|c| c.prompt());
                 if let Some(p) = prompt {
                     self.command_line.push_info(&p);