chore: add flake for development reproducibility

.envrc

@@ -0,0 +1,5 @@
+has nix && use flake
+dotenv_if_exists .env # You can create a .env file with your env vars for this project. You can also use .secrets if you are using act. See the line below.
+dotenv_if_exists .secrets # Used by [act](https://nektosact.com/) to load secrets into the pipelines
+
+export GITHUB_STEP_SUMMARY=/tmp/github_summary.html

flake.nix

@@ -0,0 +1,34 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    utils.url = "github:numtide/flake-utils";
+  };
+  outputs = {
+    self,
+    nixpkgs,
+    utils,
+  }:
+    utils.lib.eachDefaultSystem (
+      system: let
+        pkgs = import nixpkgs {
+          inherit system;
+          config.allowUnfree = true;
+        };
+      in {
+        devShells.default = with pkgs;
+          mkShell {
+            buildInputs =
+              [
+                typescript
+                nodejs_20
+              ]
+              ++ (with nodePackages; [
+                typescript-language-server
+                eslint
+              ]);
+          };
+
+        formatter = pkgs.alejandra;
+      }
+    );
+}