Introduced a new testing strategy for the data access layer to avoid redundant testing of generic repository methods.
- Created a comprehensive test suite for the generic `BaseRepository` using a dedicated `TestEntity`. This suite covers all common CRUD operations, including transactions and error handling, in a single location.
- Added a new, focused test suite for `CategoryRepository` that only tests its repository-specific methods, relying on the base repository tests for generic functionality.
- Refactored the existing `AuthorRepository` test suite to remove redundant CRUD tests, aligning it with the new, cleaner pattern.
- Updated the test utilities to support the new testing strategy.
This change significantly improves the maintainability and efficiency of the test suite and provides a clear, future-proof pattern for testing all repositories.
