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)

templates/pages/page-download-file.php

@@ -3,7 +3,7 @@
  * Template Name: AKSRT - 单篇资源下载
  * Template Post Type: page
  *
- * Zibll pages/download.php equivalent.
+ * legacy pages/download.php equivalent.
  * URL: {page}?post={post_id}
  * Only for pay_type=download posts. Shows download buttons when allowed,
  * or a no-permission state with a back link to the article.
@@ -43,7 +43,7 @@ $article_url = get_permalink($post) . '#posts-pay';
 $pay_title   = get_the_title($post);
 $subtitle    = '';
 if (function_exists('get_the_subtitle')) {
-	// noop — AKSRT may not have zibll subtitle helper
+	// noop — AKSRT may not have legacy subtitle helper
 }
 $has_access = function_exists('aksrt_has_paid_access') ? aksrt_has_paid_access($post) : false;
 $gate       = function_exists('aksrt_can_download') ? aksrt_can_download($post) : true;