refactor(nix): simplify package declaration

nix/package.nix

@@ -1,26 +1,36 @@
 {
   pkgs,
-  rustPlatform,
+  nativeRustPlatform,
+  windowsRustPlatform,
   ...
 }: let
   cargoToml = fromTOML (builtins.readFile ../Cargo.toml);
   name = cargoToml.package.name;
   version = cargoToml.package.version;
-  rustBuild = rustPlatform.buildRustPackage {
+  buildArgs = {
     pname = name;
     inherit version;
     src = pkgs.lib.cleanSource ../.;
     cargoLock.lockFile = ../Cargo.lock;
-    nativeBuildInputs = [pkgs.upx];
     useNextest = true;
     meta = {
-      description = "Conventional commits for Jujutsu";
-      homepage = "https://labs.phundrak.com/phundrak/jj-cz";
+      inherit (cargoToml.package) description homepage;
     };
     postBuild = ''
       ${pkgs.upx}/bin/upx target/*/release/${name}
     '';
   };
+  nativeBuild =
+    nativeRustPlatform.buildRustPackage buildArgs
+    // {
+      postBuild = "${pkgs.upx}/bin/upx target/*/release/${name}";
+    };
+  windowsBuild =
+    windowsRustPlatform.buildRustPackage buildArgs
+    // {
+      postBuild = "${pkgs.upx}/bin/upx target/*/release/${name}.exe";
+    };
 in {
-  default = rustBuild;
+  default = nativeBuild;
+  windows = windowsBuild;
 }