stats.ctimeNs
仅在将 bigint: true 传递给生成对象的方法时才会出现。该时间戳表示文件状态最后一次更改的时间，以自 POSIX 纪元以来的纳秒为单位。
【Only present when bigint: true is passed into the method that generates
the object.
The timestamp indicating the last time the file status was changed expressed
in nanoseconds since the POSIX Epoch.】