feat(ui): compatible right-click context menu driven by command options

The viewport context menu is now built from a pure model
(ui::popup::context_menu) rendered by the overlay: while a command runs it
offers Enter / Cancel / every keyword of the command's options() with the
keyword shown as a hint, a Recent Input submenu and M2P; when idle it offers
Repeat, Recent Input, Clipboard, Undo/Redo with history labels, the edit
block (Erase/Move/Copy/Scale/Rotate/Mirror/Draw Order), Isolate, Pan/Zoom,
selection tools, Properties and Options. The default row is anchored under
the pointer and the menu is keyboard-navigable (arrows, Enter, mnemonic
letters; any other key closes it and types into the command line).

Right-click behaviour is a user preference (Options → User Preferences,
SHORTCUTMENU / SHORTCUTMENUDURATION): shortcut menu (commercial solutions default),
time-sensitive, or the previous Enter-first cycle.

LINE gains options() (Close/Undo/eXit).

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

src/app/update/file.rs

@@ -481,6 +481,8 @@ impl OpenCADStudio {
             selection_cycling: self.selection_cycling,
             double_click_block_refedit: self.double_click_block_refedit,
             double_click_block_attedit: self.double_click_block_attedit,
+            right_click_mode: self.right_click_mode,
+            right_click_hold_ms: self.right_click_hold_ms,
             grip_object_limit: self.grip_object_limit,
             ncopy_bind: self.ncopy_bind,
             cursor_type: self.cursor_type,
@@ -556,6 +558,8 @@ impl OpenCADStudio {
         self.selection_cycling = s.selection_cycling;
         self.double_click_block_refedit = s.double_click_block_refedit;
         self.double_click_block_attedit = s.double_click_block_attedit;
+        self.right_click_mode = s.right_click_mode;
+        self.right_click_hold_ms = super::super::settings::clamp_right_click_hold_ms(s.right_click_hold_ms);
         self.grip_object_limit = s.grip_object_limit.clamp(0, 32767);
         self.ncopy_bind = s.ncopy_bind;
         self.cursor_type = s.cursor_type;