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

modules/system/security/gpg/default.nix

@@ -0,0 +1,18 @@
+{ lib, config, ... }:
+
+let
+  cfg = config.systemSettings.security.gpg;
+in {
+  options = {
+    systemSettings.security.gpg = {
+      enable = lib.mkEnableOption "Enable gpg";
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    programs.gnupg.agent = {
+      enable = true;
+      enableSSHSupport = true;
+    };
+  };
+}