nixvim: add nvim-scrollbar via extraPlugins

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

modules/home/nixvim/plugins/ui/default.nix

@@ -11,5 +11,6 @@
     ./lightbulb.nix
     ./colorizer.nix
     ./dropbar.nix
+    ./scrollbar.nix
   ];
 }

modules/home/nixvim/plugins/ui/scrollbar.nix

@@ -0,0 +1,8 @@
+{ pkgs, ... }: {
+  programs.nixvim = {
+    extraPlugins = [ pkgs.vimPlugins.nvim-scrollbar ];
+    extraConfigLua = ''
+      require("scrollbar").setup()
+    '';
+  };
+}