- Added Pydantic schemas for permission-related requests and responses in `schemas.py`.
- Created seed data for various permissions and roles in `seed.py`.
- Developed a `PermissionService` class in `service.py` to handle permission logic, including user role assignments and direct permission grants.
- Implemented unit tests for permission functionalities in `test_permissions.py`, covering role assignments, permission checks, and expiration handling.
- Seeded trailer types data in `trailer_types/seed.py`.
