获取置顶会话列表

{
    "code": 1,
    "message": "置顶会话列表获取成功",
    "language": "zh-CN",
    "timestamp": 1697548800000,
    "data": [
        {
            "user_id": "user_001",
            "friend_id": "user_123456",
            "friend_name": "小张",
            "is_conversation_pinned": true,
            "update_time": "2023-10-17T12:00:00Z",
            "friendInfo": {
                "user_id": "user_123456",
                "nickname": "张三",
                "avatar": "https://example.com/avatar.jpg"
            }
        }
    ]
}