style: migrate font-size classes to text-[size] syntax

Additionally update spacing utilities and refactor the OrderQrcode component:
- Switch popup implementation from uni-popup to van-popup
- Remove the deprecated SCSS stylesheet
- Clean up component template and script code

src/components/UseDateRange/index.vue

@@ -7,16 +7,13 @@
       <scroll-div class="date-scroll" scroll-x>
         <div class="date-list">
           <block v-for="item in openDateRangeList" :key="item.date">
-            <div
-              class="date-item"
-              :class="{ selected: isSameDate(selectedDate, item.date) }"
-              @click="onDateClick(item)"
-            >
-              <div class="label font-size-12">{{ item.weekDesc }}</div>
+            <div class="date-item" :class="{ selected: isSameDate(selectedDate, item.date) }"
+              @click="onDateClick(item)">
+              <div class="label text-[12px]">{{ item.weekDesc }}</div>
               <div class="md font-size-16 font-600">
                 {{ formatMD(item.date) }}
               </div>
-              <div class="status font-size-12">{{ item.canOrder }}</div>
+              <div class="status text-[12px]">{{ item.canOrder }}</div>
               <div v-if="isSameDate(selectedDate, item.date)" class="check">
                 ✔
               </div>