feat(intercity): raise a GRN when a facility loads or unloads cargo

Every facility raises a GRN — the goods changed hands, whether or not anyone
stores them. What differs is what happens next: Indode has a warehouse, so cargo
left there goes through the existing warehouse flow and accrues storage and
demurrage; Sebeta, Modjo, Adama and Dire Dawa only move cargo between train and
truck, so the handling event and its GRN are the whole record.

facility_handling_events carries that record because warehouse_inventory cannot:
its warehouse/yard/zone are NOT NULL, so a facility with equipment but no
warehouse could never have a row there. inventory_id links the storage record
when the facility does keep the cargo, which is what ties an Indode handover to
its demurrage.

generateGrnNumber moves to common/grn.util.ts so a GRN raised at a facility is
indistinguishable from one raised in a warehouse — the two live in different
tables, and a second generator would let the formats drift.

Recording is best-effort: the cargo moved regardless, so paperwork must never
fail the journey.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/edr-freight-api/src/common/grn.util.ts

@@ -0,0 +1,13 @@
+/**
+ * Goods Received Note number: `GRN-<DIRECTION>-<YYYYMMDD>-<REF8>`.
+ *
+ * Shared so a GRN raised at a load/unload facility is indistinguishable from one
+ * raised in a warehouse — the two live in different tables
+ * (facility_handling_events vs warehouse_inventory), and a second generator would
+ * eventually let their formats drift apart.
+ */
+export function generateGrnNumber(direction: string, referenceId: string, date: Date): string {
+  const stamp = date.toISOString().slice(0, 10).replace(/-/g, '');
+  const suffix = referenceId.replace(/-/g, '').slice(0, 8).toUpperCase();
+  return `GRN-${direction.toUpperCase()}-${stamp}-${suffix}`;
+}