add devshell for nodejs

flake.nix

@@ -26,6 +26,7 @@
         haskell = import ./shells/haskell.nix { inherit pkgs; };
         python = import ./shells/python.nix { inherit pkgs; };
         rust = import ./shells/rust.nix { inherit pkgs; };
+        node = import ./shells/node.nix { inherit pkgs; };
       };
     }
   );

shells/node.nix

@@ -0,0 +1,11 @@
+{ pkgs }: pkgs.mkShell {
+  packages = with pkgs; [
+    nodejs_20
+    yarn
+  ];
+  shellHook = ''
+    export npm_config_prefix="$PWD/.nix/npm/prefix"
+    export npm_config_cache="$PWD/.nix/npm/cache"
+    export PATH="$npm_config_prefix/bin:$PATH"
+  '';
+}