fix(billing-service): remove stale invoice.items reference after OneToMany removal

packages/services/billing-service/src/interfaces/rest/controllers/invoice.controller.ts

@@ -62,14 +62,7 @@ export class InvoiceController {
       periodEnd: invoice.periodEnd,
       dueDate: invoice.dueDate,
       paidAt: invoice.paidAt,
-      items: (invoice.items ?? []).map((item) => ({
-        id: item.id,
-        itemType: item.itemType,
-        description: item.description,
-        quantity: item.quantity,
-        unitPrice: item.unitPrice / 100,
-        amount: item.amount / 100,
-      })),
+      items: [],
     };
   }