refactor: replace flex-full with flex-1 and standardize scrollbar styles

- replace all outdated flex-full utility classes with modern flex-1 across Vue components
- standardize scrollbar hiding by using scrollbar-none utility instead of verbose vendor prefixes
- update order detail page layout and scroll container styling
- add scrollbar-none usage guidelines to AGENTS.md documentation

src/pages/home/components/FaqHelpCard/index.vue

@@ -14,7 +14,7 @@
     <div class="faq-help-card__list">
       <div v-for="item in questions" :key="item.id || item.text" class="faq-help-card__item flex flex-items-center"
         :class="{ 'is-disabled': disabled }" @click="handleSelect(item)">
-        <div class="faq-help-card__question color-475569 text-[18px] font-900 truncate flex-full">
+        <div class="faq-help-card__question color-475569 text-[18px] font-900 truncate flex-1">
           {{ item.text }}
         </div>
         <uni-icons type="right" size="16" color="#CBD5E1"></uni-icons>