[Money] Day-Rate Tuition with Proration

Raised Sept 25. Childcare/MDO programs typically bill by days-per-week attendance (e.g., 2-day vs. 3-day vs. 5-day rate) rather than a flat class/semester fee, and need proration for a family starting or leaving mid-month. Distinct from Per-Class Multiple Fee Line Items & Rate Tiers (that's per-class pricing variation, not a recurring day-rate childcare billing model). Scope: a day-rate tuition model per program with mid-month proration, on top of the existing billing engine.