Feature: Implement New User Isolation for Enhanced Privacy

[Swamp2k9]

I manage multiple social groups for work, gaming, family, and more. Currently, new users are automatically placed in a default group upon signing up, which grants them access to other users' wishlists.

To enhance privacy and control, it would be beneficial to have an option to isolate new users until they are manually added to specific groups.

[cmintey]

How are users signing up? If they are signing up via a link you generate, you can select the group they'll be placed in. If they are signing up without a link then they should not be placed in any group upon signup and login.