refactor: standardize spacing and update RefundPopup component

- standardize margin spacing across components with explicit pixel values
- replace legacy uni-popup and icons with van-ui equivalents in RefundPopup
- update font weight class to use semantic name in date range selector

src/components/UseDateRange/index.vue

@@ -10,7 +10,7 @@
             <div class="date-item" :class="{ selected: isSameDate(selectedDate, item.date) }"
               @click="onDateClick(item)">
               <div class="label text-[12px]">{{ item.weekDesc }}</div>
-              <div class="md text-[16px] font-600">
+              <div class="md text-[16px] font-semibold">
                 {{ formatMD(item.date) }}
               </div>
               <div class="status text-[12px]">{{ item.canOrder }}</div>