Added flake.nix and stuff

.gitignore

@@ -0,0 +1,2 @@
+.venv/
+.vscode/

flake.nix

@@ -0,0 +1,21 @@
+{
+  description = "Python dev environment using Nix";
+
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.05";
+
+  outputs = { self, nixpkgs }: let
+    system = "x86_64-linux";
+    pkgs = import nixpkgs { inherit system; };
+  in {
+    devShells.${system}.default = pkgs.mkShell {
+      packages = [
+        (pkgs.python312.withPackages (ps: with ps; [
+          pip
+          virtualenv
+          black
+          pytest
+        ]))
+      ];
+    };
+  };
+}