Add Nix package and NixOS moodule

Add a Scribe Nix package and NixOS module to the flake that a user can
build and install.

Includes the following supporting changes:
- Adding a name and version to package.json to make Nix's mkYarnPackage
  happy
- Update laravel-mix to fix ERR_OSSL_EVP_UNSUPPORTED on newer nodejs
  versions

shell.nix

@@ -1,16 +1,16 @@
 { pkgs ? import <nixpkgs> { } }:
 
 pkgs.mkShell {
-  shellHook = ''
-    export PKG_CONFIG_PATH=${pkgs.openssl.dev}/lib/pkgconfig
-  '';
   buildInputs = with pkgs; [
     crystal
     lucky-cli
     overmind
     nodejs
-    openssl.dev
+    openssl
+    pkg-config
     shards
     yarn
+    crystal2nix
+    pcre
   ];
 }