fix(首页): 修复入场动画期间滚动锁定问题

确保在 Lenis 加载完成前后都能正确锁定页面滚动
修复滚动锁定计数逻辑，避免重复操作

app/composables/usePageScrollLock.ts

@@ -7,11 +7,11 @@ let lenisLockCount = 0
 
 export const usePageScrollLock = (isLocked: Ref<boolean> | boolean) => {
   const { $lenis } = useNuxtApp() as ReturnType<typeof useNuxtApp> & { $lenis?: Lenis }
-  
+
   // SSR 和 CSR 都支持：自动将 class 注入到 HTML 标签上
   useHead({
     htmlAttrs: {
-      class: computed(() => unref(isLocked) ? 'is-home-intro-active' : undefined)
+      class: computed(() => unref(isLocked) ? 'is-home-intro-active' : '')
     }
   })
 
@@ -23,19 +23,25 @@ export const usePageScrollLock = (isLocked: Ref<boolean> | boolean) => {
     currentlyLocked = locked
 
     // Lenis 控制仅在客户端有效
-    if (import.meta.client && $lenis) {
+    if (import.meta.client) {
       if (locked) {
         lenisLockCount++
         // 只有第一个锁请求时，才真正停止 Lenis 并滚动到顶部
         if (lenisLockCount === 1) {
-          $lenis.scrollTo(0, { immediate: true })
-          $lenis.stop()
+          document.documentElement.classList.add('is-home-intro-active')
+          if ($lenis) {
+            $lenis.scrollTo(0, { immediate: true })
+            $lenis.stop()
+          }
         }
       } else {
         lenisLockCount = Math.max(0, lenisLockCount - 1)
         // 只有当所有锁请求都释放时，才重新启动 Lenis
         if (lenisLockCount === 0) {
-          $lenis.start()
+          document.documentElement.classList.remove('is-home-intro-active')
+          if ($lenis) {
+            $lenis.start()
+          }
         }
       }
     }