Major config overhaul: use custom modules, setup for multi-host config, and less boilerplate

modules/user/terminal/kitty.nix

@@ -0,0 +1,20 @@
+{ config, lib, pkgs, ... }:
+
+let
+  cfg = config.userSettings.kitty;
+in {
+  options = {
+    userSettings.kitty = {
+      enable = lib.mkEnableOption "Enable kitty";
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    home.packages = [ pkgs.kitty ];
+    programs.kitty.enable = true;
+    programs.kitty.settings = {
+      background_opacity = lib.mkForce "0.85";
+      modify_font = "cell_width 90%";
+    };
+  };
+}