home: extract 'comma' into its own module

home/comma.nix

@@ -0,0 +1,15 @@
+{ config, lib, pkgs, ... }:
+let
+  cfg = config.my.home.comma;
+in
+{
+  options.my.home.comma = with lib; {
+    enable = my.mkDisableOption "comma configuration";
+  };
+
+  config = lib.mkIf cfg.enable {
+    home.packages = with pkgs; [
+      ambroisie.comma
+    ];
+  };
+}

home/default.nix

@@ -3,6 +3,7 @@
   imports = [
     ./bat.nix
     ./bluetooth.nix
+    ./comma.nix
     ./direnv.nix
     ./documentation.nix
     ./feh.nix

home/packages.nix

@@ -18,7 +18,6 @@ in
   };
 
   config.home.packages = with pkgs; lib.mkIf cfg.enable ([
-    ambroisie.comma
     file
     gitAndTools.git-absorb
     gitAndTools.git-revise