Add a nix flake

Author: mrinalwadhwa

.gitignore

@@ -0,0 +1,3 @@
+*.DS_store
+.envrc
+.direnv

tools/nix/flake.lock

@@ -0,0 +1,24 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs";
+  };
+
+  outputs = { self, nixpkgs }:
+    let
+      supportedSystems = [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
+      forEachSupportedSystem = f: nixpkgs.lib.genAttrs supportedSystems (system: f {
+        inherit system;
+        pkgs = import nixpkgs { inherit system; };
+      });
+    in
+    {
+      devShells = forEachSupportedSystem ({ pkgs, system }: {
+        default = pkgs.mkShell {
+          nativeBuildInputs = with pkgs; [
+            commitlint
+            eclint
+          ];
+        };
+      });
+    };
+}