fix: 显示下发智能体的云端图标

tests/unit/coding-teacher-ui.test.tsx

@@ -96,6 +96,16 @@ async function ready() {
   await waitFor(() => expect(streams.has('first')).toBe(true));
 }
 describe('teacher side chat', () => {
+  it('renders the pinned topic icon in the header and assistant messages', async () => {
+    const icon = 'https://yuxi.example.test/api/storage/public/images/topic.png';
+    api.read.mockResolvedValue({ ...first, definition: { ...definition, icon_url: icon }, requests: [request({ response: '继续原来的讨论' })] });
+    const view = render(<TeacherChatPanel projectId="p" sourceId="c" />);
+    await ready();
+    const images = view.container.querySelectorAll('[data-testid="teacher-chat-panel"] img');
+    expect(images).toHaveLength(2);
+    for (const img of images) expect(img).toHaveAttribute('src', icon);
+  });
+
   it('renders assistant Markdown, tables, code and images instead of literal markup', async () => {
     const response = '## 项目建议\n\n**先验证跳跃**\n\n- 保留现有玩法\n\n| 文件 | 用途 |\n| --- | --- |\n| main.ts | 入口 |\n\n```json\n{"name":"flybot"}\n```\n\n[说明](https://example.com/readme)\n\n![项目截图](https://example.com/preview.png)';
     api.read.mockResolvedValue({ ...first, requests: [request({ response })] });