Fixes: 1) Remove unused `django-autocompletefilter` package and adjust imports; 2) Clean up related settings and dependency references;
Extra: Minor formatting adjustments in `payments/admin.py`.
Fixes: 1) Correct use of `@action` decorator within `ActivationActionsMixin` for defining admin actions; 2) Remove unused `BasicModelAdmin` inheritance from multiple admin classes.
Extra: Refactor and simplify admin imports and site registration for better readability and maintainability.
Fixes: 1) Corrected `ForeignKey` type assertions across models; 2) Resolved typos and formatting inconsistencies in `.env` and README; 3) Fixed explicit boolean checks in user manager methods.
Extra: Updated type hints in multiple models, serializers, and views.
