refactor(assets): vendor 资产迁入标准目录并全仓去除 zibll 标识

- assets/vendor 全量迁移: fontawesome5→assets/fontawesome5, css→assets/css,
  js→assets/js/runtime(避开 14 个同名自有文件), img 合并去重→assets/img,
  fonts→assets/fonts; 删除 assets/vendor
- libs 五个与 widgets/third-party 字节相同的库不重复入库, loader paths 改指向
- 运行时切换: _win.uri=assets 根, loader baseUrl=/js/runtime, enlighter 注入
  路径同步; PHP 7 个引用文件切换并改名 $zibll_*→$runtime_*
- 去品牌: Qinver 头注释/品牌 console.log/演示链接清除, 默认文案中性化
- 功能标识符改名: zib__→aksrt__, zib_ajax→aksrt_ajax, window.zib→
  window.aksrtLegacy, zibllblock/*→aksrtblock/*, .zib-widget→.aksrt-panel,
  .zib-slider→.aksrt-slider, zib_menu_options meta 键等
- 自有 CSS 改名: legacy-utilities/compat-vars/footer shell
- admin SPA 重建; 契约测试同步(路径/断言/文件更名)
- 例外保留: tests/visual 对照环境与 fixtures 前缀(外部 Zibll 产品引用)

验证: php -l 133 个改动文件通过; runtime 86 个 JS node --check 通过;
契约测试 68/70(2 个失败经 stash 对照确认为存量问题)

src/Credits/Signin.php

@@ -156,18 +156,18 @@ class Signin {
             }
         }
 
-        // Keep lightweight meta for header/badge consumers (zibll checkin_all_day).
+        // Keep lightweight meta for header/badge consumers (legacy checkin_all_day).
         update_user_meta($user_id, 'aksrt_signin_' . $today_str, 1);
         $all_day = (int) get_user_meta($user_id, 'aksrt_checkin_all_day', true);
         if ($all_day <= 0) {
-            // Fallback to zibll key if migrated users only have that meta.
+            // Fallback to legacy key if migrated users only have that meta.
             $all_day = (int) get_user_meta($user_id, 'checkin_all_day', true);
         }
         $all_day = $all_day + 1;
         update_user_meta($user_id, 'aksrt_checkin_all_day', $all_day);
-        update_user_meta($user_id, 'checkin_all_day', $all_day); // zibll alias
+        update_user_meta($user_id, 'checkin_all_day', $all_day); // legacy alias
         update_user_meta($user_id, 'aksrt_checkin_continuous_day', $new_streak);
-        update_user_meta($user_id, 'checkin_continuous_day', $new_streak); // zibll alias
+        update_user_meta($user_id, 'checkin_continuous_day', $new_streak); // legacy alias
         do_action('aksrt_checkin_done', $user_id);
 
         return new \WP_REST_Response([
@@ -246,7 +246,7 @@ class Signin {
     }
 
     /**
-     * zibll checkin_details_modal lite HTML.
+     * legacy checkin_details_modal lite HTML.
      */
     public function render_details_modal_html(int $user_id): string {
         $user = get_userdata($user_id);