- Extend `department_selfserve_tasks_o` with `buttons` and `dynamic_images_vehicle_type` properties.
- Add normalization/validation methods for `buttons` and `dynamic_images_vehicle_type` parameters.
- Update `departmentSelfserveTasksRoute` to handle new fields in task creation and update.
- Add OpenAPI specifications for `buttons` and `dynamic_images_vehicle_type`.
- Include comprehensive tests for button normalization and vehicle type selection.