style: redesign today board as paper note

frontend/src/App.vue

@@ -1537,16 +1537,19 @@ onUnmounted(() => {
       <MemoPanel v-else-if="activeView==='memos'" ref="memoPanel" :request="api" @scope="memoTrash=$event==='trash'" @detail="memoDetailOpen=$event" @notice="toast" />
       <CountdownPanel ref="countdownComposer" v-else-if="activeView==='countdowns'" @notice="toast" />
       <template v-else>
-        <section v-if="activeView==='today'" class="today-board" aria-label="今日进度">
+        <section v-if="activeView==='today'" class="today-board" aria-labelledby="today-board-title">
+          <h2 id="today-board-title" class="sr-only">今日纸笺</h2>
           <TodayEnvironmentStrip :environment="todayEnvironment" :loading="todayEnvironmentLoading" :failed="todayEnvironmentError" />
-          <button class="today-track today-task-track" type="button" aria-controls="today-tasks" @click="navigateTodaySection('tasks')">
-            <span class="today-track-head"><strong>任务 {{ todayTaskCompleted }} / {{ todayTaskTotal }}</strong></span>
-            <span class="today-track-rail" role="progressbar" aria-label="今日任务进度" aria-valuemin="0" :aria-valuemax="todayTaskTotal" :aria-valuenow="todayTaskCompleted"><i class="today-track-fill" :style="{ width: todayTaskProgressPercent }" /></span>
-          </button>
-          <button class="today-track today-habit-track" type="button" aria-controls="today-habits" @click="navigateTodaySection('habits')">
-            <span class="today-track-head"><strong>习惯 {{ todayHabitProgress }}</strong></span>
-            <span class="today-track-rail" role="progressbar" aria-label="今日习惯进度" aria-valuemin="0" :aria-valuemax="todayHabitTotal" :aria-valuenow="todayHabitCompleted"><i class="today-track-fill" :style="{ width: todayHabitProgressPercent }" /></span>
-          </button>
+          <div class="today-board__progress" aria-label="今日任务与习惯进度">
+            <button class="today-track today-task-track" type="button" aria-controls="today-tasks" @click="navigateTodaySection('tasks')">
+              <span class="today-track-head"><strong>任务 {{ todayTaskCompleted }} / {{ todayTaskTotal }}</strong></span>
+              <span class="today-track-rail" role="progressbar" aria-label="今日任务进度" aria-valuemin="0" :aria-valuemax="todayTaskTotal" :aria-valuenow="todayTaskCompleted"><i class="today-track-fill" :style="{ width: todayTaskProgressPercent }" /></span>
+            </button>
+            <button class="today-track today-habit-track" type="button" aria-controls="today-habits" @click="navigateTodaySection('habits')">
+              <span class="today-track-head"><strong>习惯 {{ todayHabitProgress }}</strong></span>
+              <span class="today-track-rail" role="progressbar" aria-label="今日习惯进度" aria-valuemin="0" :aria-valuemax="todayHabitTotal" :aria-valuenow="todayHabitCompleted"><i class="today-track-fill" :style="{ width: todayHabitProgressPercent }" /></span>
+            </button>
+          </div>
         </section>
         <template v-if="activeView==='today'">
           <section v-if="overdueTaskTree.length" class="overdue-section today-collapsible-section">