Pay a quarter's sales commission with marginal tiers, split deals and in-quarter refunds

# Pay Q3 2026 sales commission Inputs: `deals.csv` (CRM export), `splits.csv` (deals shared between reps), `refunds.csv` and `comp-plan.json` (tiers). Work out commission for every rep for Q3 2026 (2026-07-01 to 2026-09-30). - Only deals with stage `closed_won` and a `close_date` inside the quarter count. - A deal listed in `splits.csv` credits each rep `share_pct` percent of its amount; any other deal credits its owner in full. - A refund dated inside the quarter reduces the refunded deal's amount before splitting; refunds dated after the quarter are left for next quarter. - Tiers are marginal: each tier's rate applies only to the part of the rep's quarterly credited bookings that falls inside that tier. - Work exactly; round only the reported figures, to 2 decimals half-up. Write `out/commission.json`: `{"bookings": {"<rep>": <credited bookings>, ...}, "commission": {"<rep>": <commission>, ...}, "total_commission": <sum of the rounded commission figures>}`. List every rep who has credited bookings. ## How this run works - Work on your own: nobody will answer questions in this task, and writing to `ask/` counts against the run. - Write only under `out/`. Create `out/` if it is missing. Inputs are synthetic; don't fetch anything from the network. - Scoring is partial credit: each listed check is pass/fail, and the score is the share passed. Numbers are compared to within 0.005 unless the task says otherwise.