重新设计用户/作者卡片小工具：消除多层卡片堆叠

- WidgetUserCard/WidgetAuthorCard 内层根节点去掉重复的 zib-widget widget 类
- 用户卡片补 classname=widget_aksrt_user_card 钩子
- widget-batch5.css 新增外层 .zib-widget 包裹层透明化规则（含首页侧栏覆盖）
- 内层 .aksrt-user-card/.aksrt-author-card margin-bottom 归零，间距由外层统一
- 删除 custom-amount.css 重复的 .aksrt-user-card* 段
- 删除 sidebar.css 失效的 .widget-user-card* 死代码
- author-actions.css .user-card.author.zib-widget → .user-card.author

assets/css/frontend/single-post/author-actions.css

@@ -636,7 +636,7 @@ html.dark .post-drop-meta__item:hover {
 
 
 /* ===== Zibll user-card after-box ===== */
-.user-card.author.zib-widget { margin-bottom: 16px; overflow: hidden; }
+.user-card.author { margin-bottom: 16px; overflow: hidden; }
 .user-card.author .user-avatar { display: flex; justify-content: center; }
 .user-card.author .user-avatar .avatar,
 .user-card.author .user-avatar img { width: 80px; height: 80px; border-radius: 50%; object-fit: cover; }