Function make_on_toggle_enabled 

fn make_on_toggle_enabled(
    enabled: RwSignal<bool>,
    active_source_id: RwSignal<Option<String>>,
    error_message: RwSignal<Option<String>>,
) -> impl Fn(MouseEvent) + Copy + Send + Sync + 'static

Closure factory for the master toggle. Extracted so ScreenPicker stays under the clippy::too_many_lines cap.