【反馈】普通账号关注超 99 人后的错误提示优化

{
    "c": 400,
    "m": "关注数量已达上限（99），开通 Pro 后可提升至 999",
    "d": null,
    "t": 1793349498100,
    "u": "/api/users/e8dd3359-e6b3-46d9-bd3f-80f211f072b6/follow"
}