feat(props): select whole value when a property field is clicked

Clicking an editable property value field now selects its entire value instead
of only placing the caret, so typing immediately replaces it. The click is
observed through a global left-press subscription (PropPointerPressed); a focus
sweep reports which widget took focus and PropSyncActive maps it back to the
active property row, then issues a select-all operation only when focus landed
on a different field.

The active row stays highlighted while its text input holds keyboard focus and
clears when focus moves elsewhere.

src/app/view/mod.rs

@@ -2116,6 +2116,9 @@ impl OpenCADStudio {
             event::listen_with(|ev, status, win_id| {
                 use iced::event::Status;
                 match ev {
+                    iced::Event::Mouse(iced::mouse::Event::ButtonPressed(
+                        iced::mouse::Button::Left,
+                    )) => Some(Message::PropPointerPressed),
                     iced::Event::Window(window::Event::CloseRequested) => {
                         Some(Message::WindowCloseRequested(win_id))
                     }