fix: 清理 typecheck 报错并修正迁移列名

- 加入缺失的 @testing-library/dom 依赖（RTL v16 必需 peer），修复 screen 导入
- 修正测试文件错误的相对导入路径（header 改具名导入；prompts/courses 指向 ../page）
- 修正联盟/打赏迁移 SQL：Prisma 列名为 camelCase（仅 @@map 映射表名），原 snake_case 列名导致查询 500，已重建表
- npm run typecheck 现已通过（EXIT=0）

frontend/package.json

@@ -64,6 +64,7 @@
   },
   "devDependencies": {
     "@playwright/test": "^1.60.0",
+    "@testing-library/dom": "^10.4.1",
     "@testing-library/jest-dom": "^6.9.1",
     "@testing-library/react": "^16.3.2",
     "@types/dompurify": "^3.0.5",
@@ -75,6 +76,6 @@
     "eslint": "^8.57.1",
     "eslint-config-next": "^16.2.6",
     "jsdom": "^29.1.1",
-    "vitest": "^4.1.5"
+    "vitest": "^4.1.10"
   }
 }

frontend/src/app/courses/__tests__/courses.vitest.tsx

@@ -1,6 +1,6 @@
 import { describe, it, expect, beforeAll, afterAll } from 'vitest';
 import { render, screen } from '@testing-library/react';
-import CoursesPage from '../app/courses/page';
+import CoursesPage from '../page';
 
 describe('Courses Page', () => {
   it('should render courses page', () => {

frontend/src/app/prompts/__tests__/prompts.vitest.tsx

@@ -1,6 +1,6 @@
 import { describe, it, expect } from 'vitest';
 import { render, screen } from '@testing-library/react';
-import PromptsPage from '../app/prompts/page';
+import PromptsPage from '../page';
 
 describe('Prompts Page', () => {
   it('should render prompts page', () => {

frontend/src/components/layout/__tests__/header.vitest.tsx

@@ -1,6 +1,6 @@
 import { describe, it, expect } from 'vitest';
 import { render, screen } from '@testing-library/react';
-import Header from '../header';
+import { Header } from '../header';
 
 describe('Header Component', () => {
   it('should render navigation links', () => {