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/pages/home/components/NoticeCard/index.vue

@@ -4,14 +4,14 @@
       <div class="notice-card__summary-title color-B45309 font-size-16 font-900">
         {{ summary.title }}
       </div>
-      <div class="notice-card__summary-content color-D97706 font-size-14 font-900">
+      <div class="notice-card__summary-content color-D97706 text-[14px] font-900">
         {{ summary.content }}
       </div>
       <div class="notice-card__summary-footer flex flex-items-center flex-justify-between">
-        <div class="notice-card__summary-time color-D97706 font-size-12 font-900">
+        <div class="notice-card__summary-time color-D97706 text-[12px] font-900">
           {{ summary.publishTime }}
         </div>
-        <div class="notice-card__summary-link color-B45309 font-size-14 font-900" :class="{ 'is-disabled': disabled }"
+        <div class="notice-card__summary-link color-B45309 text-[14px] font-900" :class="{ 'is-disabled': disabled }"
           @click="openDetail">
           {{ summary.actionText }}
         </div>
@@ -41,7 +41,7 @@
         </div>
         <div class="notice-card__divider"></div>
         <div v-for="paragraph in paragraphs" :key="paragraph.id"
-          class="notice-card__paragraph color-475569 font-size-14 font-800">
+          class="notice-card__paragraph color-475569 text-[14px] font-800">
           <span v-for="segment in paragraph.segments" :key="segment.text"
             :class="{ 'notice-card__strong': segment.strong }">
             {{ segment.text }}