refactor: replace custom line-height classes with tailwind leading utils

Remove the deprecated src/static/scss/line-height.scss custom utility file, and update all component template instances of line-height-* classes to use the equivalent tailwind leading-[xxpx] utilities. This standardizes line height styling across the codebase by using native tailwind classes instead of custom SCSS helpers.

src/components/RefundPopup/index.vue

@@ -2,7 +2,7 @@
   <uni-popup ref="popupRef" type="bottom" :safe-area="false" @maskClick="handleClose">
     <view class="refund-popup bg-[#f5f7fa] border-box">
       <view class="border-box flex flex-items-center justify-between pt-[12px] pb-[12px] relative">
-        <view class="flex-full font-size-16 color-171717 line-height-24 text-center">取消政策</view>
+        <view class="flex-full font-size-16 color-171717 leading-[24px] text-center">取消政策</view>
         <!-- 关闭按钮 -->
         <uni-icons class="close absolute" type="close" size="20" color="#CACFD8" @click="handleClose" />
       </view>
@@ -16,7 +16,7 @@
             {{ refundTitle }}
           </text>
         </view>
-        <view class="font-size-14 color-525866 line-height-16 mb-4"
+        <view class="font-size-14 color-525866 leading-[16px] mb-4"
           v-for="(item, index) in commodityPurchaseInstruction" :key="index">
           {{ item }}
         </view>