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/Content/VipServicePurchase.php

@@ -538,7 +538,7 @@ trait VipServicePurchase {
             delete_user_meta($user_id, 'aksrt_vip_base_expires');
         }
         $fulfilled = false;
-        // unit upgrade: raise level only, keep current expiry (zibll).
+        // unit upgrade: raise level only, keep current expiry (legacy).
         if ($upgrade_mode === 'unit') {
             $this->activate_vip($user_id, $level, 0, true);
             $fulfilled = (int) get_user_meta($user_id, 'aksrt_vip_level', true) >= $level;
@@ -598,7 +598,7 @@ trait VipServicePurchase {
         // Clear expired memory when re-granting.
         delete_user_meta($user_id, 'aksrt_vip_level_expired');
 
-        // Unit upgrade (zibll): keep vip_exp_date, only raise level.
+        // Unit upgrade (legacy): keep vip_exp_date, only raise level.
         if ($keep_expiry) {
             return;
         }
@@ -620,7 +620,7 @@ trait VipServicePurchase {
     }
 
     /**
-     * Activate VIP using calendar duration (zibll month/day).
+     * Activate VIP using calendar duration (legacy month/day).
      * time=0 → permanent. Extends from max(now, current_exp).
      */
     public function activate_vip_duration(int $user_id, int $level, int $time, string $unit = 'day'): void {