add nix flake for nix develop shell with direnv

.envrc

@@ -0,0 +1,2 @@
+#!/usr/bin/env direnv
+use flake .

flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1708807242,
+        "narHash": "sha256-sRTRkhMD4delO/hPxxi+XwLqPn8BuUq6nnj4JqLwOu0=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "73de017ef2d18a04ac4bfd0c02650007ccb31c2a",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,21 @@
+{
+  description = "runtimeterror build environment";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+  };
+
+  outputs = { self, nixpkgs }:
+  let
+    pkgs = import nixpkgs { system = "x86_64-linux"; };
+  in
+   {
+    devShells.x86_64-linux.default = pkgs.mkShell {
+      packages = with pkgs; [
+        go
+        hugo
+        nodePackages.npm
+      ];
+    };
+  };
+}