feat(M08-A): 增加权益可视化选择器

backend/src/orders/pricing-repository.ts

@@ -120,7 +120,8 @@ export class PricingRepository {
         quote = this.calculate(room, {
           ...input,
           adjustment: {
-            discountCents: benefitReservation.discountCents,
+            discountCents: benefitReservation.discountCents
+              + timeCouponDiscountCents(benefitReservation.minutes, quote.unitPriceCents),
             packageCreditCents: benefitReservation.packageCreditCents
           }
         }, isHoliday);
@@ -373,6 +374,11 @@ function clampAdjustment(value: number | undefined, maximum: number) {
   return Math.min(Math.trunc(value), maximum);
 }
 
+function timeCouponDiscountCents(minutes: number | undefined, unitPriceCents: number) {
+  if (!minutes || minutes <= 0) return 0;
+  return Math.ceil(minutes / 60) * unitPriceCents;
+}
+
 function localDateKey(date: Date, timezone: string) {
   return new Intl.DateTimeFormat('en-CA', {
     timeZone: timezone, year: 'numeric', month: '2-digit', day: '2-digit'