feat: add Container Returns page with EDR/Customer filter

Separate page for tracking empty container returns by type: EDR returns
(empty containers from EDR first-mile) or Customer returns (customer
self-haul). Segmented control filter, expandable booking rows showing
containers, modal to record return with warehouse selection. Accessible
via sidebar menu under Import Operations.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

apps/edr-freight-api/src/modules/train-scheduling/wagon-plan-flex.util.ts

@@ -415,15 +415,22 @@ export function planWagonsWithStock(params: {
  * sequenceNos, the snapshot re-sorts by them, and the board/allocation views all
  * read them — so the stored train order and the schedule order stay identical,
  * just reversed. A false/absent flag returns the plan unchanged.
+ *
+ * Only the NUMBERS flip — the array itself stays in packing order. Container
+ * placements are generated by walking the container units in booking order
+ * against getContainerSlotSequenceNos(plan) in array order, then matched back to
+ * their allocation by `sequenceNo:bookingId`. Reordering the array here broke
+ * that pairing on every reversed schedule: unit 1 was handed the number of the
+ * slot holding the LAST booking, the match missed, and persistAllocationsAndLoads
+ * silently dropped every container item — which is why a reversed export train
+ * printed a marshalling doc with no container numbers and 0/0 container counts.
  */
 export function applyWagonOrderReversal(
   plan: WagonPlanSlot[],
   reverse: boolean | null | undefined,
 ): WagonPlanSlot[] {
   if (!reverse) return plan;
-  return [...plan]
-    .reverse()
-    .map((slot, index) => ({ ...slot, sequenceNo: index + 1 }));
+  return plan.map((slot, index) => ({ ...slot, sequenceNo: plan.length - index }));
 }
 
 /** Unbounded stock — used to compute pure demand for availability reporting. */