✅ test(search): 更新搜索API测试用例断言

- 将success字段断言替换为code字段断言，验证错误状态码是否为400
- 保持错误消息验证逻辑不变，确保错误提示正确

tests/integration/server/routes/search.integration.test.ts

@@ -307,7 +307,7 @@ describe('用户端路线搜索API集成测试', () => {
       IntegrationTestAssertions.expectStatus(response1, 400);
       if (response1.status === 400) {
         const responseData = await response1.json();
-        expect(responseData.success).toBe(false);
+        expect(responseData.code).toBe(400);
         expect(responseData.message).toContain('车型必须是有效的类型');
       }
 
@@ -322,7 +322,7 @@ describe('用户端路线搜索API集成测试', () => {
       IntegrationTestAssertions.expectStatus(response2, 400);
       if (response2.status === 400) {
         const responseData = await response2.json();
-        expect(responseData.success).toBe(false);
+        expect(responseData.code).toBe(400);
         expect(responseData.message).toContain('出行方式必须是有效的类型');
       }
     });