nvim: add external formatter support

modules/programs/nvim/default.nix

@@ -44,6 +44,7 @@ in
       extraPackages = with pkgs; [
         sumneko-lua-language-server
         nil
+        stylua
       ];
       plugins = with pkgs.vimPlugins; [
         catppuccin-nvim
@@ -55,6 +56,7 @@ in
         lualine-lsp-progress
         lualine-nvim
         luasnip
+        formatter-nvim
         neogit
         noice-nvim
         nui-nvim # for noice-nvim