Refactor modules into nixos and home-manager

modules/home-manager/programs/gpg.nix

@@ -0,0 +1,22 @@
+{ config, lib, pkgs, ... }:
+
+let cfg = config.modules.programs.gpg;
+in {
+  options.modules.programs.gpg = {
+    enable = lib.mkOption {
+      default = false;
+      example = true;
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    home.programs.gpg = {
+      enable = true;
+    };
+
+    home.services.gpg-agent = {
+      enable = true;
+      enableSshSupport = true;
+    };
+  };
+}