tree-wide: format with nixfmt

Another saturday another useless formatter change.
It's my dotfiles, after all

alejandra doesn't handle c-style inline comments well.

nix/homeModules/common/kitty.nix

@@ -3,9 +3,11 @@
   lib,
   config,
   ...
-}: let
+}:
+let
   cfg = config.programs.kitty;
-in {
+in
+{
   config = lib.mkIf cfg.enable {
     home.packages = [
       pkgs.nerd-fonts.iosevka