Added the `System.ComponentModel.DataAnnotations.Schema` namespace.
Introduced new properties to the `SignatureDto` class:
- `FullName` (string?) for the full name of the signature entity.
- `Position` (string?) for the position of the signature entity.
- `Place` (string?) for the place associated with the signature entity.
- `Ink` (byte[]?) for the ink data of the signature entity.