I think both nginx (sure) and Apache (?) manage their own list of
types. The Windows registry mostly defines what the Windows explorer
should do with them. Various desktop environments of Linux have
something similar. It is non-trivial. The same extension can
represent different media types.
A clear advantage of doing it ourselves is that we can guarantee that
the application runs cross-platform. For short, I think we should, at
least for now, stick to the current approach. Of course, the list is
rather limited, so feel free to propose extensions.
Cheers --- Jan