refactor: migrate to tailwind arbitrary width classes

remove the unused src/static/scss/width.scss file and its import from index.scss, replace all existing custom width utility class usages with the equivalent Tailwind arbitrary width syntax

src/pages/ChatModule/AigcPhotoCard/index.vue

@@ -1,7 +1,7 @@
 <template>
   <view class="w-full bg-white border-ff overflow-hidden rounded-[20px] flex flex-col">
     <!-- 占位撑开 -->
-    <view class="w-vw"></view>
+    <view class="w-screen"></view>
 
     <view class="aigc-photo-card relative rounded-[24px] overflow-hidden w-full"
       :class="{ 'is-disabled': disabled, 'is-empty': !videoUrl }" @click="handleAction">