All pre-existing, all mechanical:
- pointerCursor no longer implies generation from the block alone; set enable.
- top-level elixir_1_18 alias is deprecated for the beamPackages set. Same
derivation, 1.18.4 either way.
- pkgs.system -> pkgs.stdenv.hostPlatform.system.
- fzf and atuin both bind Ctrl-R. Atuin is sourced last so it already owned the
key; historyWidget.zsh.command = "" states that explicitly and satisfies
home-manager's conflict check. Behaviour is unchanged and fzf keeps Ctrl-T
and Alt-C.