update flake.nix to allow unfree packages and add claude-code dependency

flake.nix

@@ -9,7 +9,8 @@
   outputs = { self, nixpkgs, flake-utils }:
     flake-utils.lib.eachDefaultSystem (system:
       let
-        pkgs = nixpkgs.legacyPackages.${system};
+        pkgs = import nixpkgs { inherit system; config.allowUnfree = true; };
+
 
         # QR code generator script
         qr-gen = pkgs.writeShellScriptBin "qr" ''
@@ -77,6 +78,7 @@
             qrencode
             imagemagick
             gnumake
+            claude-code
           ];
 
           shellHook = ''