feat(billing): enhance invoice payment processing and revert handling

feat(bookings): add event handlers for booking invoice payment processing
fix(bookings): include PAYMENT_VERIFICATION_IN_PROGRESS status in queries
fix(train-scheduling): update status checks to include PAYMENT_VERIFICATION_IN_PROGRESS
feat(notifier): notify customers when a train is cancelled

apps/edr-freight-api/src/modules/train-scheduling/booking-notifier.service.ts

@@ -300,6 +300,19 @@ export class BookingNotifierService {
     this.inApp(b, 'Removed from train', msg);
   }
 
+  /**
+   * The train carrying this booking was cancelled. The booking is detached and
+   * returns to the eligible pool — the customer must rebook or pick a new schedule.
+   */
+  scheduleCancelled(b: Booking): void {
+    const msg =
+      `The train for booking ${b.reference ?? b.id} has been cancelled. ` +
+      `Your booking is not lost — please rebook or select a new schedule from the portal.`;
+    void this.notifyContact(b, msg, 'TRAIN CANCELLED');
+    // HIGH: a cancelled train invalidates the customer's plans — must reach SMS/email.
+    this.inApp(b, 'Train cancelled', msg, { priority: NotificationPriority.HIGH });
+  }
+
   /**
    * The train carrying this booking was moved for maintenance to a new departure
    * date. The booking stays on the train — only the date moved.