feat: 新增抱团组件和申请助手弹窗组件

新增huddle-box和helper-pop组件，包含相关图片资源和样式调整
修复item-mj组件中itemBottom导入错误
优化移动端样式适配
更新sectionV2页面引入新组件
补充公共样式和动画效果

component/huddle-box/huddle-box.txt

@@ -0,0 +1,19 @@
+<div class="huddle-box" @click="closeGroup" v-if="state">
+    <div class="box flexflex" @click.stop="holdback">
+        <img class="bj" src="../../img/group-bj.svg" alt="">
+        <img class="bj-bottom" src="../../img/group-bottom.png" alt="">
+        <img class="top" src="../../img/group-top.png" alt="">
+        <img class="title" src="../../img/group-title.png" alt="">
+        <div class="text">抱团 / 信息共享 / 互助申学</div>
+        <div class="case flexflex">
+            <div class="QRcode flexcenter">
+                <img class="img" src="https://o.x-php.com/Zvt57TuJSUvkyhw-xG7Y2l-c-5kpcnzqqsgFptxhcq_cQnrlJKN1WgxCBq_D-81qNDQyOQ~~" alt="">
+            </div>
+            <div class="hint flexcenter">
+                <img class="img img-left" src="../../img/group-arrows.png" alt="">
+                <span class="hint-text">添加寄托葱哥进群</span>
+                <img class="img" src="../../img/group-arrows.png" alt="">
+            </div> 
+        </div>
+    </div> 
+</div>