feat(teacher): 连接 Yuxi 老师并提供项目与会话只读工具

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

@@ -3,6 +3,7 @@ import { beforeEach, describe, expect, it, vi } from 'vitest';
 import { TeacherChatPanel } from '@/pages/Chat/TeacherChatPanel';
 import type { TeacherDefinition, TeacherTopic } from '../../shared/coding-teacher';
 const api = vi.hoisted(() => ({
+  catalog: vi.fn(),
   config: vi.fn(),
   preview: vi.fn(),
   list: vi.fn(),
@@ -52,6 +53,7 @@ beforeEach(() => {
   vi.resetAllMocks();
   streams = new Map();
   api.config.mockResolvedValue({ enabled: true, published_version: 1, revision: 1, definition });
+  api.catalog.mockResolvedValue({ items: [{ teacher_id: 'one', version: 1, definition, is_default: true }] });
   api.list.mockResolvedValue({
     items: [
       { id: 'first', title: '第一个' },