[flake] fix flake to work on darwin

use yarn to install node deps

flake.nix

@@ -23,6 +23,7 @@
           purescript
           #spago-unstable
           nodejs
+          yarn
           nodePackages.npm
         ];
     
@@ -66,8 +67,9 @@
 
               echo "Installing JS Dependencies"
               #npm install
+              yarn
               # https://docs.npmjs.com/cli/v9/commands/npm-ci
-              npm ci
+              #npm ci
               #npm/bin/npm install --dev
           
               echo "Compiling"