feat: 更改为教研聊天助手；删除图标；删除助手描述

src/components/chat/WelcomeScreen.vue

@@ -2,16 +2,7 @@
   <div class="welcome-screen">
     <!-- Logo 和标题 -->
     <div class="welcome-header">
-      <div class="logo-wrapper">
-        <div class="logo-icon">
-          <Bot :size="40" />
-        </div>
-        <div class="logo-glow"></div>
-      </div>
-      <h1 class="title">大学教育助手</h1>
-      <p class="subtitle">
-        等待输入等待输入等待输入等待输入等待输入等待输入等待输入等待输入等待输入等待输入等待输入等待输入等待输入等待输入等待输入等待输入等待输入等待输入等待输入等待输入等待输入等待输入等待输入
-      </p>
+      <h1 class="title">教研聊天助手</h1>
     </div>
 
     <!-- 功能卡片 -->
@@ -63,7 +54,6 @@
 <script setup lang="ts">
 import { computed } from "vue";
 import {
-  Bot,
   MessageSquare,
   Code,
   Image,