feat(phase2): shared common-form layer + CommonWidgetFields trait for all widgets

- Extract Zibll CSF_Widget::params() common-field parity into
  inc/modules/widget-common.php (required by widgets-register.php to keep
  both files <1000 lines): subtitle, title_style(simple/big), title_highlight
  +color, title_link x3, title_link_style colors, sidebar_affix, show_type
  (all/only_pc/only_sm), show_id_type(show/hide), show_ids, animation_in,
  animation_repeat, layout_pin_pc/m, layout_bg(white/dark). Adds
  normalize_link/normalize_bg helpers, affix_attrs, common_wrapper_attr,
  render_title, animation_class. Back-compat normalizes legacy tokens
  (in_affix->sidebar_affix, pc/only_pc, include/exclude->show/hide).
- Add src/AKSRT/Widgets/Traits/CommonWidgetFields.php trait
  (render_common_form_section + update_common_fields).
- Wire all 57 widgets to use the trait; migrate the 16 hand-rolled in_affix
  implementations to shared sidebar_affix (fixes 6 latent bugs where
  in_affix was never persisted). SearchWidget intentionally skips the shared
  form section (its business show_type collides) but adopts the affix helper.
- widget_display_callback parity verified via tmp assertion script.

Refs .specs/plans/zibll-widgets-1to1.md Phase 2 (US1/US5)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/AKSRT/Widgets/WidgetAuthorCard.php

@@ -7,9 +7,12 @@
 
 namespace AKSRT\Widgets;
 
+use AKSRT\Widgets\Traits\CommonWidgetFields;
+
 defined('ABSPATH') || exit;
 
 class WidgetAuthorCard extends \WP_Widget {
+	use CommonWidgetFields;
 
 	public function __construct() {
 		parent::__construct(
@@ -84,15 +87,15 @@ class WidgetAuthorCard extends \WP_Widget {
 			? aksrt_get_user_name(['id' => $author_id, 'follow' => false, 'class' => 'flex ac jc'])
 			: '<a href="' . esc_url($home) . '">' . esc_html($user->display_name) . '</a>';
 
-		$in_affix = !empty($instance['in_affix']);
+		$affix = function_exists('aksrt_widget_affix_attrs') ? aksrt_widget_affix_attrs($instance) : ['class' => '', 'attr' => ''];
 		echo $args['before_widget']; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
 		$title = apply_filters('widget_title', (string) ($instance['title'] ?? ''), $instance, $this->id_base);
 		if ($title !== '') {
 			echo $args['before_title'] . esc_html($title) . $args['after_title']; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
 		}
 
-		$card_cls = 'aksrt-author-card user-card author zib-widget' . ($show_bg ? ' has-cover' : '') . ($in_affix ? ' is-affix' : '');
-		echo '<div class="' . esc_attr($card_cls) . '"' . ($in_affix ? ' data-affix="true"' : '') . '>';
+		$card_cls = 'aksrt-author-card user-card author zib-widget' . ($show_bg ? ' has-cover' : '') . $affix['class'];
+		echo '<div class="' . esc_attr($card_cls) . '"' . $affix['attr'] . '>';
 		if ($show_bg) {
 			$bg = $cover !== '' ? ' style="background-image:url(' . esc_url($cover) . ')"' : '';
 			echo '<div class="aksrt-author-card__cover user-cover graphic"' . $bg . '></div>';
@@ -210,9 +213,7 @@ class WidgetAuthorCard extends \WP_Widget {
 				</select>
 			</label>
 		</p>
-		<p>
-			<label><input type="checkbox" name="<?php echo esc_attr($this->get_field_name('in_affix')); ?>" value="1" <?php checked(!empty($instance['in_affix'])); ?>> <?php esc_html_e('侧栏随动', 'aksrt'); ?></label>
-		</p>
+		<?php $this->render_common_form_section($instance); ?>
 		<?php
 	}
 
@@ -225,7 +226,7 @@ class WidgetAuthorCard extends \WP_Widget {
 		if (!in_array($orderby, ['date', 'views', 'comment_count', 'modified', 'rand'], true)) {
 			$orderby = 'date';
 		}
-		return [
+		return $this->update_common_fields($new_instance, $old_instance, [
 			'title'       => sanitize_text_field((string) ($new_instance['title'] ?? '')),
 			'user_id'     => max(0, (int) ($new_instance['user_id'] ?? 0)),
 			'show_img_bg' => !empty($new_instance['show_img_bg']) ? 1 : 0,
@@ -236,6 +237,6 @@ class WidgetAuthorCard extends \WP_Widget {
 			'limit'       => max(0, min(12, (int) ($new_instance['limit'] ?? 6))),
 			'post_style'  => $post_style,
 			'orderby'     => $orderby,
-		];
+		]);
 	}
 }