Compute library overdue fines with renewals, closed days, grace periods and hand-typed patron ids

# Library overdue fines across branches Inputs: `loans.csv`, `renewals.csv`, `rates.json` (per item type: fine per day, cap per loan, grace days), `calendar.json` (closed dates and the as-of date). Rules: - Patron ids were typed by hand at different branches: "P-0412", "p0412", "P 412" and "P0412" are the same patron. Report ids as "P" followed by 4 digits (e.g. "P0412"). - A loan's due date is its original due date unless it was renewed. With several renewals, the one with the latest `renewed_at` timestamp sets the due date (staff corrections can move it earlier). File order means nothing. - Open days are all dates except Sundays and the dates in calendar.json `closed`. - Late open days = open days after the due date, up to and including the return date (or the as-of date if the item is not returned). - The first `grace_days` late open days are free. Fine = per_day x the remaining late open days, but never more than the item type's cap. - capped_loans = loans whose fine hit the cap, sorted by loan_id. - A patron is blocked when their total fines are 10.00 or more. Write `out/fines.json`: `{"patrons": {"<P####>": <total fines>, ...}, "blocked": [<P####>, ...], "capped_loans": [<loan_id>, ...], "total_usd": <n>}`. List only patrons with a total above 0. blocked is sorted. ## 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.