fix(CollapsibleCalendar): 调整日历弹窗位置和样式

将弹窗位置从顶部改为底部，并添加圆角样式，同时微调高度为55%

 <!--
  * @Date: 2025-01-25 15:34:17
  * @LastEditors: hookehuyr hookehuyr@gmail.com
- * @LastEditTime: 2025-12-11 17:56:07
+ * @LastEditTime: 2025-12-14 22:08:03
  * @FilePath: /mlaj/src/components/ui/CollapsibleCalendar.vue
  * @Description: 可折叠日历组件
 -->
 <template>
     <div class="collapsible-calendar ">
         <!-- 折叠状态显示 -->
-        <div v-if="!isExpanded" class="calendar-collapsed">
+        <div class="calendar-collapsed">
             <div class="calendar-header">
                 <div class="calendar-icon">
                     <svg width="20" height="20" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg">
@@ -55,8 +55,9 @@
         <!-- 展开状态的弹窗 -->
         <van-popup
             v-model:show="isExpanded"
-            position="top"
-            :style="{ height: '60%' }"
+            position="bottom"
+            round
+            :style="{ height: '55%' }"
             @close="collapseCalendar"
         >
             <div class="calendar-popup-content">