- Introduced `prepareForValidation` method to handle input merging for `behind_traefik` and `devices`.
- Updated validation rules to conditionally require `subdomain` based on `behind_traefik`.
- Added custom attribute names and error messages for better user feedback.
- Improved the create VM form to dynamically show/hide subdomain fields based on the `behind_traefik` checkbox state.
- Adjusted the user selection logic to display a message when no customers are available.
