refactor: replace border-box with box-border and clean up unused scss

Remove the unused box-sizing.scss stylesheet and its import from the main SCSS index file.
Update all Vue component template class references from the custom border-box class to the
native box-border utility class to eliminate redundant custom CSS and align with the project's
utility class conventions.

src/pages-booking/index.vue

@@ -6,7 +6,7 @@
       </template>
     </TopNavBar>
 
-    <view class="booking-content flex-full border-box p-[12px] overflow-hidden scroll-y">
+    <view class="booking-content flex-full box-border p-[12px] overflow-hidden scroll-y">
       <!-- 预约内容 -->
       <view class="border-box bg-white p-[12px] rounded-12 mb-12">
         <!-- 酒店类型入住离店日期部分 -->
@@ -25,7 +25,7 @@
           <!-- 权益部分 -->
           <view class="flex flex-items-center mb-8">
             <text
-              class="bg-[#f7f7f7] border-box rounded-4 font-size-11 color-525866 mr-4 pt-[4px] pb-[4px] pl-[6px] pr-[6px]"
+              class="bg-[#f7f7f7] box-border rounded-4 font-size-11 color-525866 mr-4 pt-[4px] pb-[4px] pl-[6px] pr-[6px]"
               v-for="(item, index) in orderData.commodityFacilityList" :key="index">
               {{ item }}
             </text>