Fix pure eval and harden nix script bootstrap

flake.nix

@@ -1,11 +1,7 @@
 {
   
   description = "LAN NixOS configs";
-      nixConfig = {
-        access-tokens = [
-          "github.com=***REMOVED***"
-        ];
-      };          
+  # GitHub tokens must be provided outside this repository (local nix.conf, env, or deployment secrets).
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.11";
     nixos-conf-editor.url = "github:snowfallorg/nixos-conf-editor";