feat(train-scheduling): auto-place intercity cargo on wagons freed mid-corridor

Intercity bookings ride the wagons freed by earlier unloads (e.g. import
containers uncoupled at Dire Dawa). loadBooking now auto-allocates a
DOMESTIC booking onto on-train slots whose cargo has all departed —
greedy in consist order by capacity, container numbers copied for the
marshalling tally. Falls back to unallocated load when nothing is free.

apps/edr-freight-web/backoffice/src/constants/URLS.ts

@@ -416,6 +416,8 @@ export const URL_CONSTANTS = {
       `/train-scheduling/schedules/${id}/import-djibouti/load-list/document`,
     EXPORT_LOAD_LIST_DOCUMENT: (id: string) =>
       `/train-scheduling/schedules/${id}/export/load-list/document`,
+    INTERCITY_MARSHALLING_DOCUMENT: (id: string) =>
+      `/train-scheduling/schedules/${id}/intercity/marshalling/document`,
     CHECKPOINTS: (id: string) =>
       `/train-scheduling/schedules/${id}/checkpoints`,
     ARRIVE: (id: string) => `/train-scheduling/schedules/${id}/arrive`,