Dividir a fatura do movimento de acordo com o centro de custo

Mirror this cost-center movement's split onto its attached invoice (Z_InvoicesCostCenter) so the dashboard 'IVA Deduzido' divides the IVA.

Only the origin PV of the parent movement may trigger it — the same rule as editing the movement split itself. Idempotent: recomputing produces the same rows.

?force=true makes it an explicit recompute request: it lifts a suppression (a split the user previously removed on the fatura) and replaces a pre-migration split. It still refuses to overwrite one entered by hand in the invoice UI — that one is only editable where it was made.