Add default nix shell (for nix develop)

flake.nix

@@ -41,5 +41,6 @@
 
   outputs = {self, nixpkgs, ...} @ inputs: {
     nixosConfigurations = import ./hosts {inherit inputs;};
+    devShells = import ./shells {inherit inputs;};
   };
 }

shells/default.nix

@@ -0,0 +1,21 @@
+{inputs, ...}: let 
+  inherit (inputs) nixpkgs;
+
+  system = "x86_64-linux";
+  pkgs = nixpkgs.legacyPackages.${system};
+in {
+  ${system} = {
+    default = pkgs.mkShell {
+      name = "nixdots";
+      meta.description = "The default development shell for my NixOS configuration";
+      packages = with pkgs; [
+        git # flakes require git
+        nil # nix ls
+        statix # lints and suggestions
+        deadnix # clean up unused nix code
+        alejandra # nix formatter
+      ];
+      shellHook = "exec $SHELL";
+    };
+  };
+}