修复 H5 嵌入小程序导航栏冲突

- 识别微信小程序 web-view 宿主环境
- 宿主导航存在时隐藏 H5 自绘返回与页面标题
- 收回详情、搜索、讲解列表页面顶部预留空间

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/pages/hall/detail.vue

@@ -264,7 +264,7 @@ const handleBack = () => {
 
 .content {
   height: 100%;
-  padding: 84px 20px calc(28px + env(safe-area-inset-bottom));
+  padding: var(--guide-page-detail-top-padding, 84px) 20px calc(28px + env(safe-area-inset-bottom));
   box-sizing: border-box;
 }