refactor(App.vue): 移除Epub标签以简化章节面板头部

src/App.vue

@@ -187,7 +187,6 @@ function handleImportSuccess(importData) {
     <el-card class="chapter-panel" shadow="never">
       <template #header>
         <div class="panel-header">
-          <span>Epub</span>
           <div class="header-buttons">
             <el-button 
               type="success"