feat: implement staff price adjustment feature for bookings

apps/edr-freight-web/backoffice/src/services/bookings.service.ts

@@ -208,6 +208,13 @@ export const bookingsService = {
   staffReject: (id: string, reason: string) =>
     postBooking<BookingDetail>(B.STAFF_REJECT(id), { reason }),
 
+  /** Adjust a booking's total price (pass null amount to clear the adjustment). */
+  adjustPrice: (id: string, amount: number | null, reason?: string) =>
+    postBooking<BookingDetail>(`/bookings/${id}/adjust-price`, {
+      amount,
+      reason,
+    }),
+
   approveStep: ({ id, stepId, requiredRole }: ApproveStepPayload) =>
     postBooking<BookingDetail>(B.APPROVE_STEP(id, stepId), { requiredRole }),