rest of the split migration

modules/shell/config/home.nix

@@ -0,0 +1,20 @@
+{
+  inputs,
+  lib,
+  osConfig ? null,
+  ...
+}:
+let
+  shellType = inputs.self.lib.hmShellType osConfig "bash";
+in
+{
+  options.my.shell.type = lib.mkOption {
+    type = lib.types.enum [
+      "bash"
+      "zsh"
+    ];
+    default = "bash";
+    description = "The shell to use in Home Manager";
+  };
+  config.my.shell.type = lib.mkDefault shellType;
+}