feat(chat): simplify teacher pane and color follow-up cards

tests/unit/teacher-companion.test.tsx

@@ -77,7 +77,7 @@ describe('teacher presence and periodic guidance', () => {
     expect(api.checkIn).not.toHaveBeenCalled();
     await act(async () => fireEvent.click(experience));
     expect(screen.queryByTestId('teacher-introduction')).not.toBeInTheDocument();
-    expect(screen.getByRole('heading', { name: '体验朋友' })).toBeVisible();
+    expect(screen.getByRole('complementary', { name: '体验朋友咨询' })).toBeVisible();
     // The first move may arrive only after the click when crossing a tooltip's
     // grace area. It must not reopen the introduction beneath the pointer.
     fireEvent.pointerMove(experience, { pointerType: 'mouse' });
@@ -145,7 +145,7 @@ describe('teacher presence and periodic guidance', () => {
     expect(second).toHaveAttribute('src', b.definition.icon_url);
     await act(async () => fireEvent.click(screen.getByRole('button', { name: '与另一个智能体聊天' })));
     const images = view.container.querySelectorAll('[data-testid="teacher-chat-panel"] img');
-    expect(images).toHaveLength(2);
+    expect(images).toHaveLength(1);
     for (const img of images) expect(img).toHaveAttribute('src', b.definition.icon_url);
   });
 
@@ -160,7 +160,7 @@ describe('teacher presence and periodic guidance', () => {
     expect(screen.getByRole('button', { name: '与体验朋友聊天' })).toBeVisible();
     await act(async () => fireEvent.click(screen.getByRole('button', { name: '与体验朋友聊天' })));
     expect(screen.queryByLabelText('新话题使用的智能体')).not.toBeInTheDocument();
-    expect(screen.getByRole('heading', { name: '体验朋友' })).toBeVisible();
+    expect(screen.getByRole('complementary', { name: '体验朋友咨询' })).toBeVisible();
     fireEvent.change(screen.getByLabelText('向智能体提问'), { target: { value: '体验的草稿' } });
     await act(async () => fireEvent.click(screen.getByRole('button', { name: '与方法老师聊天' })));
     expect(screen.getByLabelText('向智能体提问')).toHaveValue('');
@@ -192,13 +192,13 @@ describe('teacher presence and periodic guidance', () => {
     await mount();
     await act(async () => fireEvent.click(screen.getByRole('button', { name: '与方法老师聊天' })));
     expect(api.read).toHaveBeenCalledWith('project', oldA.id);
-    expect(screen.getByRole('heading', { name: '方法老师' })).toBeVisible();
+    expect(screen.getByRole('complementary', { name: '方法老师咨询' })).toBeVisible();
     fireEvent.change(screen.getByLabelText('向智能体提问'), { target: { value: '继续原来的讨论' } });
     await act(async () => fireEvent.click(screen.getByRole('button', { name: '提问', exact: true })));
     expect(api.send.mock.calls[0][1]).toBe(oldA.id);
     expect(api.create).not.toHaveBeenCalled();
     await act(async () => fireEvent.click(screen.getByRole('button', { name: '与体验朋友聊天' })));
-    expect(screen.getByRole('heading', { name: '体验朋友' })).toBeVisible();
+    expect(screen.getByRole('complementary', { name: '体验朋友咨询' })).toBeVisible();
     expect(api.read).toHaveBeenCalledWith('project', oldB.id);
   });
 
@@ -213,7 +213,7 @@ describe('teacher presence and periodic guidance', () => {
     await mount();
     await act(async () => fireEvent.click(screen.getByRole('button', { name: '与体验朋友聊天' })));
     await act(async () => resolve(old));
-    expect(screen.getByRole('heading', { name: '体验朋友' })).toBeVisible();
+    expect(screen.getByRole('complementary', { name: '体验朋友咨询' })).toBeVisible();
     expect(screen.getByRole('button', { name: '与体验朋友聊天' })).toHaveAttribute('aria-pressed', 'true');
     expect(api.read).toHaveBeenCalledWith('project', old.id, false);
     expect(api.send).not.toHaveBeenCalled();