refactor: 自定义组卷工具条行收敛到AppStack

client/src/views/practice/CustomView.vue

@@ -86,12 +86,12 @@ function back() {
 
     <template v-else>
       <!-- 工具条 -->
-      <div class="custom__toolbar">
+      <AppStack direction="row" gap="space-3" class="custom__toolbar">
         <span class="custom__count">已选 <b>{{ selectedCount }}</b> / 20 题</span>
         <AppButton variant="secondary" size="md" @click="toggleAll">
           {{ selectedCount === items.length ? '取消全选' : `全选（前20题）` }}
         </AppButton>
-      </div>
+      </AppStack>
 
       <!-- 题目列表 -->
       <div class="custom__list">
@@ -130,10 +130,8 @@ function back() {
 
 <style scoped>
 .custom__toolbar {
-  display: flex;
-  align-items: center;
-  justify-content: space-between;
-  gap: var(--space-3);
+  --stack-align: center;
+  --stack-justify: space-between;
 }
 .custom__count {
   font-size: var(--fs-subtitle);