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/Feedback/index.vue

@@ -9,13 +9,13 @@
       </div>
 
       <div v-if="!isCallSuccess" class="border-box p-12">
-        <div class="bg-F5F7FA border-box flex flex-items-center p-12 rounded-10 font-size-14 color-171717 mb-12">
+        <div class="bg-F5F7FA border-box flex flex-items-center p-12 rounded-10 text-[14px] color-171717 mb-12">
           <span class="font-500 line-height-22 mr-20">联系电话</span>
           <input placeholder="请填写联系电话" v-model="contactPhone" />
         </div>
-        <div class="bg-F5F7FA border-box p-12 rounded-10 font-size-14 font-500 color-171717 mb-12">
+        <div class="bg-F5F7FA border-box p-12 rounded-10 text-[14px] font-500 color-171717 mb-12">
           <div class="font-500 line-height-22 mb-12">意见内容</div>
-          <textarea class="h-80" placeholder="请输入反馈意见" placeholder-class="font-size-14 font-400" maxlength="100"
+          <textarea class="h-80" placeholder="请输入反馈意见" placeholder-class="text-[14px] font-400" maxlength="100"
             v-model="contactText" />
         </div>
 
@@ -26,17 +26,17 @@
       </div>
 
       <div v-else class="border-box left flex-full p-12">
-        <div class="font-size-12 color-525866 line-height-20 mb-4">
+        <div class="text-[12px] color-525866 line-height-20 mb-4">
           联系方式: {{ contactPhone }}
         </div>
-        <div class="font-size-12 color-525866 line-height-20 ellipsis-2">
+        <div class="text-[12px] color-525866 line-height-20 ellipsis-2">
           意见内容: {{ contactText }}
         </div>
       </div>
 
       <div class="footer-help flex flex-items-center pl-12 mb-12">
         <img class="help-icon mr-4" src="./images/icon_volume.png" />
-        <span class="font-size-12 font-500 color-FA7319">
+        <span class="text-[12px] font-500 color-FA7319">
           {{ appName }}收到您的意见将第一时间为您处理!
         </span>
       </div>