redesign module hierarchy

nix/snow/flake/modules/devShells.nix

@@ -1,30 +1,35 @@
-{ lib, flake-parts-lib, ... }:
-let
-  inherit (lib)
+{
+  lib,
+  snow,
+  ...
+}: let
+  inherit
+    (lib)
     mkOption
     types
     literalExpression
     ;
-  inherit (flake-parts-lib)
-    mkTransposedPerSystemModule
+  inherit
+    (snow)
+    mkPerSystemFlakeOutput
     ;
 in
-mkTransposedPerSystemModule {
-  name = "devShells";
-  option = mkOption {
-    type = types.lazyAttrsOf types.package;
-    default = { };
-    description = ''
-      An attribute set of packages to be used as shells.
-      [`nix develop .#<name>`](https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-develop.html) will run `devShells.<name>`.
-    '';
-    example = literalExpression ''
-      {
-        default = pkgs.mkShell {
-          nativeBuildInputs = with pkgs; [ wget bat cargo ];
-        };
-      }
-    '';
-  };
-  file = ./devShells.nix;
-}
+  mkPerSystemFlakeOutput {
+    name = "devShells";
+    option = mkOption {
+      type = types.lazyAttrsOf types.package;
+      default = {};
+      description = ''
+        An attribute set of packages to be used as shells.
+        [`nix develop .#<name>`](https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-develop.html) will run `devShells.<name>`.
+      '';
+      example = literalExpression ''
+        {
+          default = pkgs.mkShell {
+            nativeBuildInputs = with pkgs; [ wget bat cargo ];
+          };
+        }
+      '';
+    };
+    file = ./devShells.nix;
+  }