Creates a new contract under the target legal entity, plus its first contract version, effective on the given date. The employee's own legal entity follows on that date, when the new version becomes their reference contract version — so the employee still belongs to the previous legal entity until then. The country data of the new version is resolved against the target legal entity's template, so fields that only existed under the previous one are dropped. Requires the legal entity change feature to be enabled for the company.