cerulean now manages trivial home-manager options

cerulean/home/default.nix

@@ -0,0 +1,20 @@
+# NOTE: you can access the system configuration via the `osConfig` arg
+{
+  username,
+  lib,
+  ...
+}: {
+  # WARNING: required for home-manager to work
+  programs.home-manager.enable = true; # user must apply lib.mkForce
+  # Nicely reload systemd units when changing configs
+  systemd.user.startServices = lib.mkDefault "sd-switch";
+
+  home = {
+    username = lib.mkDefault username;
+    homeDirectory = lib.mkDefault "/home/${username}";
+
+    sessionVariables = {
+      NIX_SHELL_PRESERVE_PROMPT = lib.mkDefault 1;
+    };
+  };
+}