fix(payments): reconcile with gateway before expiring unpaid holds

Replace the fixed 5-minute grace with a settlement check at expiry:
expire() calls the payment API's reconcile endpoint — paid intents are
kept and allocated via payment.succeeded, unverifiable results defer
expiry to the next tick, only verifiably unpaid holds expire.

apps/edr-freight-api/src/modules/train-scheduling/booking-batch.constants.ts

@@ -9,14 +9,6 @@
 
 export const BATCH_TIMEZONE = 'Africa/Addis_Ababa';
 
-/**
- * Slack after a booking's paymentDeadline before the settle sweep expires it.
- * Covers gateway/webhook lag for a payment STARTED inside the window —
- * initiation itself is hard-blocked at the deadline (BillingService.payInvoice),
- * so this never extends the time a customer has to begin paying.
- */
-export const PAYMENT_GRACE_MS = 5 * 60_000;
-
 /** How long before the pay deadline the one reminder notification goes out. */
 export const PAYMENT_REMINDER_LEAD_MS = 10 * 60_000;