Fixes: 1) Fix email validation to properly handle `self.instance` checks in serializers;
Extra: 1) Remove unnecessary blank lines and reformat code for better readability; 2) Consolidate migration field definitions to a single line for cleaner diff;
Fixes: 1) Correct verbose_name usage for `attributes` field in an existing model;
Extra: 1) Adjust admin field grouping and formatting consistency for readability.