Fix missing vi imports in test files

Co-authored-by: huangyiirene <7665279+huangyiirene@users.noreply.github.com>

Author: Copilot

packages/renderer/src/__tests__/registry.test.tsx

@@ -1,4 +1,4 @@
-import { describe, it, expect, beforeEach } from 'vitest';
+import { describe, it, expect, beforeEach, vi } from 'vitest';
 import React from 'react';
 import { render, screen } from '@testing-library/react';
 import { ComponentRegistry } from '../registry';

packages/ui/src/__tests__/button.test.tsx

@@ -1,4 +1,4 @@
-import { describe, it, expect } from 'vitest';
+import { describe, it, expect, vi } from 'vitest';
 import React from 'react';
 import { render, screen } from '@testing-library/react';
 import { Button } from '../components/ui/button';