High accuracy timestamp support for messages

Optional, like:
|*| CE 1970-01-01 00:00:00 UTC
|*| CE 2021-03-05 09:30:00 -05:00

Over something fuzzy like "Yesterday 3:45 AM".

[ Note:

The CE (Common Era) indication would be necessary for prospective purpose:

It's unlikely for a timestamp in the future be expressed in a manner like "14625819242-01-01" commonly.

Some schema like "CE (1,462,728) 1970-01-01" shall be introduced for representing the very timestamp absolutely. And a simple year notation like "1970" typically refers to the current CE iteration only. ]