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/modules/draw/modify/mirror.rs

@@ -125,6 +125,15 @@ impl CadCommand for MirrorCommand {
         matches!(self.step, Step::AskErase { .. })
     }
 
+    fn options(&self) -> Vec<crate::command::CmdOption> {
+        use crate::command::CmdOption;
+        if matches!(self.step, Step::AskErase { .. }) {
+            vec![CmdOption::new("Yes", "Y"), CmdOption::new("No", "N")]
+        } else {
+            Vec::new()
+        }
+    }
+
     fn on_text_input(&mut self, text: &str) -> Option<CmdResult> {
         let Step::AskErase { p1, p2 } = &self.step else {
             return None;