feat(widgets): marketing card empty states + feature intro media lazy

Admin null shells for feature/highlights/cover/icon/combo/tilt/buttons
and video player; feature intro lazy images + deferred inactive videos.

src/AKSRT/Widgets/WidgetIconCoverCards.php

@@ -29,6 +29,13 @@ class WidgetIconCoverCards extends \WP_Widget {
 	public function widget($args, $instance): void {
 		$cards = $this->normalize($instance['cards'] ?? []);
 		if (!$cards) {
+			if (current_user_can('manage_options')) {
+				echo $args['before_widget']; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
+				echo function_exists('aksrt_get_widget_null')
+					? aksrt_get_widget_null(__('请添加至少一张图标封面卡', 'aksrt')) // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
+					: '<p class="widget-empty">' . esc_html__('请添加至少一张图标封面卡', 'aksrt') . '</p>';
+				echo $args['after_widget']; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
+			}
 			return;
 		}
 		$pc_row = max(1, min(4, (int) ($instance['pc_row'] ?? 2)));