add nix devshell (flake based)

flake.nix

@@ -0,0 +1,27 @@
+# Template: https://nixos-and-flakes.thiscute.world/development/intro
+{
+  description = "Dev Shell for dobutterfliescry.net";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-25.05";
+  };
+
+  outputs = {nixpkgs, ...}: let
+    system = "x86_64-linux";
+  in {
+    devShells."${system}".default = let
+      pkgs = import nixpkgs {
+        inherit system;
+      };
+    in
+      pkgs.mkShell {
+        packages = with pkgs; [
+          bash
+          simple-http-server
+          imagemagick
+        ];
+
+        shell = "${pkgs.bash}/bin/bash";
+      };
+  };
+}