major restructuring for using snowfall

modules/home/topgrade/default.nix

@@ -0,0 +1,24 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let cfg = config.modules.topgrade;
+in {
+  options.modules.topgrade = { enable = mkOption { default = false; }; };
+
+  config = mkIf cfg.enable {
+    programs.topgrade = {
+      enable = true;
+      settings = {
+        misc.no_self_update = true;
+
+        git = {
+          # Additional git repositories to pull
+          repos = [ "~/.dotfiles" ];
+
+          pull_only_repos = [ "~/dev/*" ];
+        };
+      };
+    };
+  };
+}