chore: add flake

flake.nix

@@ -0,0 +1,44 @@
+{
+  description = "Wallaby";
+
+  inputs = {
+    beam-flakes = {
+      url = "github:mhanberg/nix-beam-flakes";
+      inputs.flake-parts.follows = "flake-parts";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+    flake-parts.url = "github:hercules-ci/flake-parts";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+  };
+
+  outputs = inputs @ {
+    beam-flakes,
+    flake-parts,
+    ...
+  }:
+    flake-parts.lib.mkFlake {inherit inputs;} {
+      imports = [beam-flakes.flakeModule];
+
+      systems = ["aarch64-darwin" "x86_64-darwin" "x86_64-linux"];
+
+      perSystem = {
+        pkgs,
+        system,
+        ...
+      }: {
+        beamWorkspace = {
+          enable = true;
+          devShell = {
+            packages = with pkgs; [
+              chromedriver
+              selenium-server-standalone
+            ];
+            languageServers.elixir = false;
+            languageServers.erlang = false;
+          };
+
+          versions = {fromToolVersions = ./.tool-versions;};
+        };
+      };
+    };
+}