feat: 文件夹双策略识别 + 布局选项 + 移除提交率卡片 + localStorage缓存层

- 文件夹识别：mode 含 'folder' 优先，缺省时用 parentId 引用反推；
  即使卷王版本无 mode 字段也能正确分组，避免'直接没有文件夹选项'
- 布局选项：工具栏新增 #layoutSel（默认 / 成绩明细与缺考名单同行），
  用 CSS Grid 双模式渲染，窄屏回落单列；偏好写 localStorage
- 移除统计卡片中的提交率卡片（卡片数 9 → 8）
- localStorage 缓存层：问卷列表 / 每个项目数据 / 看板数据 / 班级组别
  筛选 / 布局 / 上次项目 id 全部持久化；进入页面先渲染缓存，
  后台再异步拉新数据并写回缓存；网络失败时仍能用本地缓存查看
- dashboard.php 同步：文件夹识别 / 数据缓存一致更新

index.php

@@ -75,6 +75,13 @@ $rosterCount = Roster::count();
       <label>组别</label>
       <select id="grpSel"><option value="">全部组别</option></select>
     </div>
+    <div class="field">
+      <label>布局</label>
+      <select id="layoutSel">
+        <option value="default">默认（缺考+未匹配同行）</option>
+        <option value="side">成绩明细与缺考名单同行</option>
+      </select>
+    </div>
     <div class="field">
       <label>自动刷新</label>
       <div class="inline">
@@ -108,7 +115,6 @@ $rosterCount = Roster::count();
     <div class="card accent-blue"><span>名单总人数</span><b id="sTotal">-</b></div>
     <div class="card ok accent-green"><span>已提交</span><b id="sSubmit">-</b></div>
     <div class="card warn accent-orange"><span>缺考</span><b id="sAbsent">-</b></div>
-    <div class="card accent-purple"><span>提交率</span><b id="sRate">-</b></div>
     <div class="card accent-teal"><span>平均分</span><b id="sAvg">-</b></div>
     <div class="card accent-green"><span>最高分</span><b id="sMax">-</b></div>
     <div class="card accent-red"><span>最低分</span><b id="sMin">-</b></div>
@@ -116,31 +122,31 @@ $rosterCount = Roster::count();
     <div class="card accent-gray"><span>平均用时</span><b id="sDur">-</b></div>
   </section>
 
-  <section class="panel">
-    <div class="panel-head">
-      <h2>成绩明细 <small id="tableHint"></small></h2>
-      <div class="updated">最后更新：<span id="lastUpdate">—</span><i id="liveDot" class="dot"></i></div>
-    </div>
-    <div class="table-scroll">
-      <table class="grid" id="dataTable">
-        <thead>
-          <tr>
-            <th class="sortable" data-k="sid">学号</th>
-            <th class="sortable" data-k="name">姓名</th>
-            <th class="sortable" data-k="cls">班级</th>
-            <th class="sortable" data-k="grp">组别</th>
-            <th class="sortable" data-k="score">成绩</th>
-            <th class="sortable" data-k="submit_ts">提交时间</th>
-            <th class="sortable" data-k="duration">考试时长</th>
-          </tr>
-        </thead>
-        <tbody id="tbody"><tr><td colspan="7" class="empty">请选择问卷 / 考试</td></tr></tbody>
-      </table>
-    </div>
-  </section>
+  <div class="layout" id="dataLayout" data-layout="default">
+    <section class="panel" id="tablePanel">
+      <div class="panel-head">
+        <h2>成绩明细 <small id="tableHint"></small></h2>
+        <div class="updated">最后更新：<span id="lastUpdate">—</span><i id="liveDot" class="dot"></i></div>
+      </div>
+      <div class="table-scroll">
+        <table class="grid" id="dataTable">
+          <thead>
+            <tr>
+              <th class="sortable" data-k="sid">学号</th>
+              <th class="sortable" data-k="name">姓名</th>
+              <th class="sortable" data-k="cls">班级</th>
+              <th class="sortable" data-k="grp">组别</th>
+              <th class="sortable" data-k="score">成绩</th>
+              <th class="sortable" data-k="submit_ts">提交时间</th>
+              <th class="sortable" data-k="duration">考试时长</th>
+            </tr>
+          </thead>
+          <tbody id="tbody"><tr><td colspan="7" class="empty">请选择问卷 / 考试</td></tr></tbody>
+        </table>
+      </div>
+    </section>
 
-  <div class="grid-2">
-    <section class="panel">
+    <section class="panel" id="absentPanel">
       <div class="panel-head"><h2>缺考名单 <small id="absentHint"></small></h2></div>
       <div class="table-scroll short">
         <table class="grid compact">
@@ -149,7 +155,8 @@ $rosterCount = Roster::count();
         </table>
       </div>
     </section>
-    <section class="panel">
+
+    <section class="panel" id="unmatchedPanel">
       <div class="panel-head"><h2>未匹配答卷 <small>姓名不在名单中</small></h2></div>
       <div class="table-scroll short">
         <table class="grid compact">