Replaced specific username checks for "Administrator" with `is_superuser`
attribute to determine admin access. This improves security and flexibility
by leveraging Django's built-in permissions and roles system, facilitating
maintenance and potential role adjustments without code changes.
Add the Coin model to the Django admin interface for easier management of coin data through the admin panel. This provides administrators with a graphical interface to directly view, edit, and maintain instances of the Coin model within the application.