users.conf sets every new user's default shell to zsh regardless of
which desktop environment they choose, but zsh was never actually
guaranteed to be installed — this locks users out at their very first
login (pam_shells.so rejects the shell before the password is even
checked). Fixed by ensuring zsh is present for every install, not
just KDE.
Also adds linux-firmware, without which GPU/wifi/etc. drivers can
fail to initialize entirely on first boot.
John
c47eb92169