refactor: remove font-size utility file and replace with inline text classes

Delete the src/static/scss/font-size.scss utility file, and replace all legacy `font-size-*` class usages across the codebase with inline `text-[numberpx]` styling to consolidate font size definitions and remove redundant utility code.

src/pages/ChatModule/AnswerComponent/index.vue

@@ -5,19 +5,19 @@
     <view class="flex flex-col px-[16px] pt-[16px] pb-[12px] border-box" @click="lookDetailAction">
       <view v-if="tag" class="long-answer-tag" :style="longAnswerTagStyle">{{ tag }}</view>
       <view v-if="title" class="flex flex-row flex-items-start flex-justify-start mb-[4px]">
-        <text class="font-size-16 font-[600] text-[#0B5C2D]"> {{ title }}</text>
+        <text class="text-[16px] font-[600] text-[#0B5C2D]"> {{ title }}</text>
       </view>
       <!-- 文字内容，根据数据模式限制预览行数 -->
-      <view v-if="processedContent" class="answer-content font-size-12 font-color-600" :style="answerContentStyle">
+      <view v-if="processedContent" class="answer-content text-[12px] font-color-600" :style="answerContentStyle">
         <ChatMarkdown :text="processedContent" :fontColor="'#94A3B8'" />
       </view>
       <!-- 超过2行时显示...提示 -->
       <view v-if="!finish" class="flex flex-row flex-items-center mt-[8px]">
-        <text class="font-size-12 font-[500] font-color-600">正在生成</text>
+        <text class="text-[12px] font-[500] font-color-600">正在生成</text>
         <ChatLoading />
       </view>
       <view v-if="isOverflow" class="flex flex-row flex-items-center flex-justify-between mt-[12px]">
-        <text class="font-size-12 font-bold text-[#cbd5e1] mr-[4px]">查看完整{{ tag }}</text>
+        <text class="text-[12px] font-bold text-[#cbd5e1] mr-[4px]">查看完整{{ tag }}</text>
         <uni-icons type="right" size="16" color="#CBD5E1"></uni-icons>
       </view>