- Update unique constraint on `PersonIdentifier` to use `canonical` instead of `value`.
- Refactor repository method `findByDefinitionAndValue` to `findByDefinitionAndCanonical`, updating logic accordingly.
- Adjust validation logic in `UniqueIdentifierConstraintValidator` to align with the new canonical-based approach.
- Modify related integration and unit tests to support the changes.
- Inject `PersonIdentifierManagerInterface` into the repository to handle canonical value generation.
- Introduce `UniqueIdentifierConstraint` and its validator for ensuring identifier uniqueness.
- Add a database-level unique constraint on `PersonIdentifier` (`definition_id`, `value`).
- Implement repository method to fetch identifiers by definition and value.
- Include integration and unit tests for validation and repository functionality.
- Update `Person` entity with `Assert\Valid` annotation for `identifiers`.