refactor: 移除 Study 和 Review 页面大标题

- 页面标题统一由全局页头展示，移除各页面内 h1
- 刷新按钮迁移至操作区/工具栏，功能不变
- Study 页开始任务改为软导航 router.push

src/components/Review.vue

@@ -42,13 +42,10 @@ onMounted(() => {
 
 <template>
   <section class="review-page">
-    <header class="surface-card review-head">
-      <div>
-        <h1 class="page-title">复习总览</h1>
-        <p class="page-subtitle">根据学习报告与残片数量，快速识别需要回顾的任务</p>
-      </div>
-      <el-button type="success" plain :loading="loading" @click="loadTasks">刷新</el-button>
-    </header>
+    <div class="table-toolbar">
+      <span class="toolbar-placeholder"></span>
+      <el-button type="success" plain size="small" :loading="loading" @click="loadTasks">刷新</el-button>
+    </div>
 
     <div class="summary-grid">
       <article class="surface-card metric-card">
@@ -83,12 +80,9 @@ onMounted(() => {
   gap: 14px;
 }
 
-.review-head {
-  padding: 20px 22px;
+.table-toolbar {
   display: flex;
-  align-items: flex-start;
-  justify-content: space-between;
-  gap: 12px;
+  justify-content: flex-end;
 }
 
 .summary-grid {
@@ -122,9 +116,5 @@ onMounted(() => {
   .summary-grid {
     grid-template-columns: 1fr;
   }
-
-  .review-head {
-    flex-direction: column;
-  }
 }
 </style>