test: テストの後片付けを強化 (CodeRabbit 指摘対応)

FadeIn / SlideIn / useReducedMotion テストで window.matchMedia と
fake timer の状態が他テストにリークしていた問題を修正:

- afterEach で originalMatchMedia へ復元
- vi.runOnlyPendingTimers() → vi.useRealTimers() の順で fake timer をクリア
- vi.restoreAllMocks() でモックを完全リセット

Author: claude

src/components/animations/FadeIn.test.tsx

@@ -2,6 +2,8 @@ import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
 import { render, screen, act } from '@testing-library/react';
 import { FadeIn } from './FadeIn';
 
+const originalMatchMedia = window.matchMedia;
+
 const mockMatchMedia = (matches: boolean) => {
   window.matchMedia = vi.fn().mockImplementation((query: string) => ({
     matches,
@@ -22,7 +24,10 @@ describe('FadeIn', () => {
   });
 
   afterEach(() => {
+    vi.runOnlyPendingTimers();
     vi.useRealTimers();
+    window.matchMedia = originalMatchMedia;
+    vi.restoreAllMocks();
   });
 
   it('renders children', () => {

src/components/animations/SlideIn.test.tsx

@@ -2,6 +2,8 @@ import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
 import { render, screen, act } from '@testing-library/react';
 import { SlideIn } from './SlideIn';
 
+const originalMatchMedia = window.matchMedia;
+
 const mockMatchMedia = (matches: boolean) => {
   window.matchMedia = vi.fn().mockImplementation((query: string) => ({
     matches,
@@ -22,7 +24,10 @@ describe('SlideIn', () => {
   });
 
   afterEach(() => {
+    vi.runOnlyPendingTimers();
     vi.useRealTimers();
+    window.matchMedia = originalMatchMedia;
+    vi.restoreAllMocks();
   });
 
   it('renders children', () => {

src/hooks/useReducedMotion.test.ts

@@ -1,7 +1,9 @@
-import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
 import { renderHook } from '@testing-library/react';
 import { useReducedMotion } from './useReducedMotion';
 
+const originalMatchMedia = window.matchMedia;
+
 const createMock = (matches: boolean) => ({
   matches,
   media: '(prefers-reduced-motion: reduce)',
@@ -18,6 +20,11 @@ describe('useReducedMotion', () => {
     window.matchMedia = vi.fn(() => createMock(false)) as unknown as typeof window.matchMedia;
   });
 
+  afterEach(() => {
+    window.matchMedia = originalMatchMedia;
+    vi.restoreAllMocks();
+  });
+
   it('returns false when prefers-reduced-motion is not set', () => {
     const { result } = renderHook(() => useReducedMotion());
     expect(result.current).toBe(false);