feat(options): menu bar, ribbon and HPASSOC switches; see-through command line by default

Options > Display gains Window Elements with "Show the menu bar"
(MENUBAR) and "Show the ribbon" (RIBBON / RIBBONCLOSE); Options > User
Preferences gains a Hatch switch for HPASSOC. The command line now
starts at 80 % opacity so the drawing shows through it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app/update/mod.rs

@@ -9082,6 +9082,24 @@ impl OpenCADStudio {
                 Task::none()
             }
 
+            Message::MenuBarChanged(shown) => {
+                self.show_menu_bar = shown;
+                self.persist_settings_if_changed();
+                Task::none()
+            }
+
+            Message::RibbonVisibleChanged(shown) => {
+                self.ribbon_closed = !shown;
+                self.persist_settings_if_changed();
+                Task::none()
+            }
+
+            Message::HatchAssociativeChanged(associative) => {
+                self.hatch_associative = associative;
+                self.persist_settings_if_changed();
+                Task::none()
+            }
+
             Message::TouchpadPanChanged(enabled) => {
                 self.touchpad_pan = enabled;
                 self.persist_settings_if_changed();