BAI-15: group mentor answer bubbles

Co-authored-by: multica-agent <github@multica.ai>

app/frontend/pages/mentor/page.html

@@ -33,16 +33,7 @@
         </aside>
 
         <section class="mentor-chat-panel" aria-label="问师对话">
-          <header class="mentor-chat-header">
-            <div class="mentor-chat-identity">
-              <span id="activeMentorAvatar" class="mentor-avatar" aria-hidden="true">师</span>
-              <div>
-                <div class="mentor-active-title"><h3 id="activeMentorName">--</h3><span id="activeMentorBadges" class="mentor-active-badges"></span></div>
-                <p id="activeMentorStatus">思维模型已就绪</p>
-              </div>
-            </div>
-            <button id="clearMentorChatButton" class="icon-button mentor-clear-button" type="button" disabled aria-label="清空当前对话" title="清空对话"><i data-lucide="trash-2"></i></button>
-          </header>
+          <p id="activeMentorStatus" class="visually-hidden" aria-live="polite">思维模型已就绪</p>
           <div id="mentorMessages" class="mentor-messages" aria-live="polite"></div>
           <div id="mentorQuickPrompts" class="mentor-quick-prompts">
             <span class="mentor-prompt-label">开始一个话题</span>
@@ -56,6 +47,7 @@
             <textarea id="mentorQuestion" maxlength="2000" placeholder="输入市场、板块、个股代码或交易问题"></textarea>
             <div class="mentor-composer-actions">
               <span>Enter 发送 · Shift + Enter 换行</span>
+              <button id="clearMentorChatButton" class="icon-button mentor-clear-button" type="button" disabled aria-label="清空当前对话" title="清空对话"><i data-lucide="trash-2"></i></button>
               <button id="stopMentorQuestion" class="button ghost mentor-stop-button" type="button" hidden><i data-lucide="square"></i><span>停止</span></button>
               <button id="sendMentorQuestion" class="button primary mentor-send-button" type="submit"><i data-lucide="send-horizontal"></i><span>发送</span></button>
             </div>