feat：新浮窗，和切换语言，和个人中心的字体统一旧函数方法删除

src/components/layout/AppHeader.vue

@@ -251,10 +251,7 @@ const toggleMobileMenu = () => {
   mobileMenuOpen.value = !mobileMenuOpen.value
 }
 
-// 切换语言下拉框
-const toggleLanguageDropdown = () => {
-  showLanguageDropdown.value = !showLanguageDropdown.value
-}
+
 
 // 处理语言选择
 const handleLanguageSelect = (lang: string) => {
@@ -281,10 +278,7 @@ const getLanguageName = (lang: string): string => {
   return languageMap[lang] || '中文'
 }
 
-// 切换语言（保留兼容性）
-const switchLanguage = (lang: string) => {
-  handleLanguageSelect(lang)
-}
+
 
 const handleLearningCenter = () => {
   console.log('学习中心被点击了')