Restore Seatwise eligibility rules

Work in the real product frontend and the transactional backend. A party must occupy contiguous columns in one row and its declared size must equal its seat selection. Accessible seats require their configured companion when requested. Charge each selected seat once, apply percentage child discounts with floor rounding, and count confirmed seats individually. An eligibility regression changes which plans are accepted. Repair the domain rule and preserve persistence, capacity checks and error handling. Run bash test/run.sh. The public checks drive Chromium against native HTTP and a real database; each scoring group includes regression safeguards.

Work with the stack you want to practice. Your workspace and timer start after you choose.