feat: bundle nodejs_16 slim with copilot & move copilot to maximal

modules/assistant/copilot.nix

@@ -13,11 +13,15 @@ in {
   };
 
   config = mkIf cfg.enable {
-    vim.startPlugins = ["copilot-lua"];
+    vim.startPlugins = [
+      "copilot-lua"
+      pkgs.nodejs-slim-16_x
+    ];
 
     vim.luaConfigRC.copilot = nvim.dag.entryAnywhere ''
       require("copilot").setup({
         -- available options: https://github.com/zbirenbaum/copilot.lua
+        copilot_node_command = "${lib.getExe pkgs.nodejs-slim-16_x}",
       })
     '';
   };