chore: add nix flake + lock

flake.nix

@@ -0,0 +1,34 @@
+{
+  description = "Next.js development environment with Podman";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+    # Systems support
+    systems.url = "github:nix-systems/default";
+  };
+
+  outputs = { self, nixpkgs, systems, flake-utils, ... }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          buildInputs = with pkgs; [
+            # Core dependencies
+            nodejs_20
+            nodePackages.typescript
+            podman
+            podman-compose
+            direnv
+            git
+          ];
+
+          # Add environment variables
+          env = {
+            NODE_ENV = "production";
+          };
+        };
+      });
+}