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)

header.php

@@ -1,6 +1,6 @@
 <?php
 /**
- * Site header: document shell + zibll-contract top navigation.
+ * Site header: document shell + legacy-contract top navigation.
  *
  * @package AKSRT
  */
@@ -30,7 +30,7 @@ if (class_exists('\AKSRT\Settings\Settings') && method_exists('\AKSRT\Settings\S
 $aksrt_has_initial_theme = in_array($aksrt_initial_theme_mode, ['dark', 'light'], true);
 
 $aksrt_body_classes = [];
-// Zibll: body.nav-fixed drives top padding + hero pull-under-nav.
+// legacy: body.nav-fixed drives top padding + hero pull-under-nav.
 if (!isset($aksrt_header_settings['nav_fixed']) || !empty($aksrt_header_settings['nav_fixed'])) {
 	$aksrt_body_classes[] = 'nav-fixed';
 } else {