feat(train-scheduling): add direct truck-to-train load action beside Load

Export bookings whose cargo goes straight from customer truck to wagon
never get a warehouse GRN, so the load gate (assertExportReceivedWithGrn)
rejects them forever unless staff first flip exportHandoverMode on the
booking detail page, then come back and retry Load.

Add a Truck to Train button next to Load in the schedule workspace's
on-train list, shown for EXPORT bookings at the boarding yard. One click
sets exportHandoverMode=DIRECT_TO_TRAIN then loads the booking.

apps/edr-freight-web/backoffice/src/components/trainScheduling/ScheduleWorkspacePanel.tsx

@@ -29,6 +29,7 @@ import {
   // Repeat, // used by the hidden Move (reassign) button
   Train,
   TrainFront,
+  Truck,
   Weight,
   X,
 } from "lucide-react";
@@ -37,6 +38,7 @@ import { CountdownTimer } from "@edr/ui-common";
 
 import { BookingStatusBadge } from "@/components/bookings/BookingStatusBadge";
 import { api } from "@/services/api";
+import { bookingsService } from "@/services/bookings.service";
 import { useToast } from "@/hooks/use-toast";
 import type {
   EligibleContainerBooking,
@@ -411,6 +413,31 @@ export function ScheduleWorkspacePanel({
       );
   };
 
+  // Export cargo that skipped the warehouse (customer truck straight onto the
+  // wagon) has no GRN and never will — loadBooking's GRN gate would keep
+  // rejecting it forever. Setting DIRECT_TO_TRAIN tells that gate the carriage
+  // acceptance sheet is the handover document instead, then loads in one click.
+  const [truckToTrainPending, setTruckToTrainPending] = useState<string | null>(null);
+  const doTruckToTrain = (bookingId: string, ref: string) => {
+    setTruckToTrainPending(bookingId);
+    bookingsService
+      .setExportHandoverMode(bookingId, "DIRECT_TO_TRAIN")
+      .then(() => loadJourney.mutateAsync({ scheduleId: schedule.id, bookingId }))
+      .then(() => {
+        toast({ title: `${ref} loaded — direct truck-to-train handover` });
+        onChanged();
+        void yardWorkQuery.refetch();
+      })
+      .catch((error) =>
+        toast({
+          title: "Could not load as direct truck-to-train",
+          description: apiErrorMessage(error, "Please try again."),
+          variant: "destructive",
+        }),
+      )
+      .finally(() => setTruckToTrainPending(null));
+  };
+
   const doUnload = (bookingId: string, ref: string) => {
     unloadJourney
       .mutateAsync({ scheduleId: schedule.id, bookingId })
@@ -708,6 +735,12 @@ export function ScheduleWorkspacePanel({
                     const alightHere = trainAtYardId != null && b.destinationYardId === trainAtYardId;
                     const showLoad = canWork && !riding && !done && (journey?.canLoad ?? false);
                     const showUnload = canWork && riding && (journey?.canUnload ?? false);
+                    const showTruckToTrain =
+                      canWork &&
+                      !riding &&
+                      !done &&
+                      boardHere &&
+                      b.tradeDirection === "EXPORT";
                     return (
                       <BookingCard
                         key={b.id}
@@ -764,6 +797,24 @@ export function ScheduleWorkspacePanel({
                                 </Button>
                               </Tooltip>
                             ) : null}
+                            {showTruckToTrain ? (
+                              <Tooltip
+                                label="Customer truck loaded straight onto the wagon — no warehouse receipt, no GRN. Sets direct truck-to-train handover and loads."
+                                withArrow
+                              >
+                                <Button
+                                  size="compact-sm"
+                                  variant="light"
+                                  color="blue"
+                                  radius="md"
+                                  leftSection={<Truck size={13} />}
+                                  loading={truckToTrainPending === b.id}
+                                  onClick={() => doTruckToTrain(b.id, ref)}
+                                >
+                                  Truck to Train
+                                </Button>
+                              </Tooltip>
+                            ) : null}
                             {showUnload ? (
                               <Tooltip
                                 label={