feat: rewired up the billing and payment with the booking

packages/types/src/freight/index.ts

@@ -140,11 +140,18 @@ export enum InvoiceStatus {
 /** Originating subsystem an invoice bills for; namespaces invoice events. */
 export enum InvoiceSource {
   Booking = "booking",
-  Contract = "contract",
   Warehouse = "warehouse",
   Demurrage = "demurrage",
 }
 
+/**
+ * What an invoice bills for within its source — the discriminator when one
+ * entity carries several invoices (e.g. a booking's up-front vs final charge).
+ */
+export enum InvoiceType {
+  Prepaid = "PREPAID",
+}
+
 export enum SchedulingStatus {
   NotScheduled = "NOT_SCHEDULED",
   Holding = "HOLDING",