StockPlanReturnToPool

Join on security_id to the compensation family. Carta has no return-to-pool transaction; Option/RSU quantity still maps to returnedToPoolQuantity. The pool-summary definition and SAR transaction-item definition were removed, so stock_plan_id and the entire SAR route are explicitly excluded.

Repeated return events are summed into the aggregate and cannot be reconstructed as individual events. date and reason_text have no target; SAR quantity and OCF scaffolding remain unmappable.