Introduced interfaces for audit fields (AddedWhen, ChangedWhen, ChangedWho, AddedWho) and updated domain entities to implement them. Adjusted properties for consistency and nullability. Updated MappingProfile to map audit fields between DTOs and entities. Improves auditability and standardization across the domain model.
- Added `X`, `Y`, `Width`, and `Height` properties with `float` database mapping.
- Retains existing fields and database annotations.
- Prepares the entity for spatial layout handling in documents.
