feat: add packages from flake

pkgs/enigma.nix

@@ -0,0 +1,42 @@
+{
+  stdenv,
+  fetchurl,
+  jdk,
+  makeWrapper,
+  makeDesktopItem,
+  copyDesktopItems,
+}:
+stdenv.mkDerivation (finalAttrs: {
+  name = "enigma";
+  version = "2.5.0";
+
+  src = fetchurl {
+    url = with finalAttrs; "https://maven.fabricmc.net/cuchaz/enigma-swing/${version}/enigma-swing-${version}-all.jar";
+    hash = "sha256-yOPPTKt96aRSbziYDBLBKqfLS2R9GeXgz5m2t1fgFHo=";
+  };
+
+  dontUnpack = true;
+
+  nativeBuildInputs = [makeWrapper copyDesktopItems];
+
+  installPhase = with finalAttrs; ''
+    runHook preInstall
+
+    mkdir -p $out/bin $out/share/${name}
+    cp ${src} $out/share/${name}/${name}.jar
+    makeWrapper ${jdk}/bin/java $out/bin/${name} --add-flags "-jar $out/share/${name}/${name}.jar"
+
+    runHook postInstall
+  '';
+
+  desktopItems = [
+    (makeDesktopItem {
+      name = "enigma";
+      desktopName = "Enigma";
+      exec = "enigma";
+      terminal = false;
+    })
+  ];
+
+  meta.mainProgram = "enigma";
+})