build(nix): Add Nix Flakes & nix-direnv dev shell

.envrc

@@ -0,0 +1,9 @@
+# shellcheck shell=bash
+if ! has nix_direnv_version || ! nix_direnv_version 2.2.1; then
+  source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/2.2.1/direnvrc" "sha256-zelF0vLbEl5uaqrfIzbgNzJWGmLzCmYAkInj/LNxvKs="
+fi
+
+dotenv_if_exists
+
+use flake
+nix_direnv_watch_file ./shell.nix

.gitignore

@@ -2,5 +2,17 @@ node_modules
 .DS_Store
 .env
 /messages
-dist
-.jest
+.jest
+
+# yarn
+.yarn/cache
+.yarn/unplugged
+.yarn/build-state.yml
+.yarn/install-state.gz
+.pnp.*
+
+# direnv
+.direnv
+
+# nix
+result

flake.nix

@@ -0,0 +1,27 @@
+{
+  description = "Validator Ejector";
+
+  inputs = {
+    nixpkgs.url = github:NixOS/nixpkgs/nixos-unstable;
+
+    flake-parts = {
+      url = "github:hercules-ci/flake-parts";
+      inputs.nixpkgs-lib.follows = "nixpkgs";
+    };
+  };
+
+  outputs = inputs @ {flake-parts, ...}:
+    flake-parts.lib.mkFlake {inherit inputs;} {
+      systems = ["x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin"];
+      perSystem = {pkgs, ...}: let
+        nodejs = pkgs.nodejs_20;
+        yarn = pkgs.yarn.override {inherit nodejs;};
+      in {
+        devShells.default = pkgs.mkShellNoCC {
+          packages = [nodejs yarn];
+        };
+
+        packages.validator-ejector = pkgs.callPackage ./packages/validator-ejector {};
+      };
+    };
+}