feat(statusbar): quick properties floating panel (QP pill)

When the QP pill is on, a compact floating panel appears at the canvas
top-left on selection, reusing the docked panel's editable section rows.
Toggleable from the status-bar customization menu.

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

src/app/update.rs

@@ -3590,6 +3590,10 @@ impl OpenCADStudio {
                 }
                 Task::none()
             }
+            Message::ToggleQuickProperties => {
+                self.quick_properties ^= true;
+                Task::none()
+            }
             Message::ToggleUnitsPopup => {
                 self.units_popup_open ^= true;
                 Task::none()