[raspberry] add base image

i currently try building it and then check if it works

outputs.nix

@@ -17,8 +17,10 @@ in (utils.lib.eachSystem (builtins.filter filter_system utils.lib.defaultSystems
     devShells.default = pkgs.callPackage ./shell.nix {
       inherit (sops-nix.packages."${pkgs.system}") sops-import-keys-hook ssh-to-pgp sops-init-gpg-key;
     };
-  })) // {
+  })) // rec {
     nixosConfigurations = import ./machines/configuration.nix (inputs // {
       inherit inputs;
     });
+
+    images.rpi1_base_image = nixosConfigurations.rpi1_base_image.config.system.build.sdImage;
 }