Explicitly enable terraform and typst version displays (if in directory
with terraform state files or .typ files for typst), and change the
symbol for the typst module to a feather (which is much nicer than the
plain 't' it would display otherwise).
Added little single-character displays at the front of the prompt if we
are in a shell different from zsh to remind myself (since they all look
exactly the same with starship).
