Idea: part of day, translatable

Currently I'm missing the part which can determine whether it is morning, afternoon, evening or night. It would also be nice if the outcome would be translatable, so it can be used in apps like:

`$dayjs().daypart() + $user.firstname`

resulting in: "Goodmorning John"

The issue names no files, tests, or entry points. Start by locating the existing date and translation APIs, then clarify the boundaries for morning, afternoon, evening, and night and how translations should be selected. Done means a daypart API exists with translatable results suitable for the example use case.

Written by the indexing model from the issue text.