Synthesises default :create and :update actions on BaseCharacteristic-derived resources from the resource's declared public attributes.

:create accepts [:name | <public_attrs>] with :instance_id and :feature_id :uuid arguments and corresponding manage_relationship changes. :update accepts <public_attrs> only.

Consumers that declare their own :create or :update action take precedence — add_new_action/4 will not replace an existing one.

System attributes (:id, timestamps, the BaseCharacteristic :name slot) are excluded from the synthesised lists; :name is included on :create only.