add boilerplate generation CLI

modules/packages/boilerplate/default.nix

@@ -0,0 +1,32 @@
+{ self, inputs, ... }:
+{
+  perSystem =
+    { pkgs, lib, ... }:
+    {
+      packages.boilerplate = pkgs.stdenvNoCC.mkDerivation {
+        pname = "boilerplate";
+        version = "0.1.0";
+
+        src = ./.;
+
+        dontConfigure = true;
+        dontBuild = true;
+
+        installPhase = ''
+          runHook preInstall
+
+          substituteInPlace boilerplate.py \
+            --replace-fail '#!/usr/bin/env python3' '#!${pkgs.python3}/bin/python3'
+          install -Dm755 boilerplate.py "$out/bin/boilerplate"
+
+          runHook postInstall
+        '';
+
+        meta = {
+          description = "Generate boilerplate Nix modules";
+          license = lib.licenses.mit;
+          mainProgram = "boilerplate";
+        };
+      };
+    };
+}