feat(reports): record loading and unloading time per stop

The OCC report publishes total loading and unloading time and the other
activity left over from a station stay, but nothing recorded when handling
started or ended — the July 2026 seed had to write the figure into a
checkpoint note. Four nullable stamps now ride the stop's arrival row, which
is the row the staying-time report builds a stay from (a turnaround's
departure belongs to a different schedule).

Handling is unloading start to loading end, so a container stop reads as one
window and a bulk station that only loads or only unloads still reports its
half; other activity is the rest of the stay. Both stay NULL where nothing
was logged rather than collapsing to zero.

- station-staying-time: + loading/unloading and other activity per stop
- turnaround-cycle: + the same, summed over the cycle's stops
- loading-unloading (new): per train per station per period, so a week or
  month view is that train's average over its stops
- the stop/stay query moves to operations-classification, shared by both

apps/edr-freight-web/backoffice/src/pages/trainScheduling/TrainScheduleTrackPage.tsx

@@ -33,7 +33,11 @@ import { PageContainer } from "@/components/page";
 import { CheckpointTimeModal } from "@/components/trainScheduling/CheckpointTimeModal";
 import { LogPassYardWorkModal } from "@/components/trainScheduling/LogPassYardWorkModal";
 import { RouteCorridorTrack } from "@/components/trainScheduling/RouteCorridorTrack";
-import type { TrackStation, TrainCheckpoint } from "@/types/trainScheduling";
+import type {
+  CheckpointHandlingTimes,
+  TrackStation,
+  TrainCheckpoint,
+} from "@/types/trainScheduling";
 import {
   RouteCorridor,
   StatusPill,
@@ -46,6 +50,51 @@ import { useToast } from "@/hooks/use-toast";
 import { openPdfBlob } from "@/components/warehouses/pdf";
 import { trainSchedulingService } from "@/services/trainScheduling.service";
 
+type CheckpointModalValues = { occurredAt: string; note: string } & Required<
+  Record<keyof CheckpointHandlingTimes, string | null>
+>;
+
+/**
+ * The station-work stamps off the modal.
+ *
+ * On an edit a cleared picker means "remove this stamp", so nulls are sent.
+ * On a first log there is nothing to remove, and the record endpoint takes no
+ * nulls — the untouched pickers are dropped instead.
+ */
+const pickHandling = (
+  values: CheckpointModalValues,
+  keepNulls: boolean,
+): CheckpointHandlingTimes =>
+  Object.fromEntries(
+    (
+      [
+        "unloadingStartedAt",
+        "unloadingCompletedAt",
+        "loadingStartedAt",
+        "loadingCompletedAt",
+      ] as const
+    )
+      .map((field) => [field, values[field]] as const)
+      .filter(([, value]) => keepNulls || value !== null),
+  );
+
+/**
+ * Total loading and unloading at a stop, the way the reports measure it:
+ * earliest start to latest finish, so a stop that only loaded or only unloaded
+ * still reads. Null when nothing was logged.
+ */
+const handlingHours = (cp: TrainCheckpoint): number | null => {
+  const times = [cp.unloadingStartedAt, cp.loadingStartedAt]
+    .filter((v): v is string => Boolean(v))
+    .map((v) => new Date(v).getTime());
+  const ends = [cp.loadingCompletedAt, cp.unloadingCompletedAt]
+    .filter((v): v is string => Boolean(v))
+    .map((v) => new Date(v).getTime());
+  if (!times.length || !ends.length) return null;
+  const hours = (Math.max(...ends) - Math.min(...times)) / 3_600_000;
+  return Math.round(hours * 10) / 10;
+};
+
 const parseError = (error: unknown, fallback: string) => {
   if (isAxiosError(error)) {
     const data = error.response?.data as Record<string, unknown> | undefined;
@@ -262,7 +311,7 @@ export default function TrainScheduleTrackPage() {
     setLogModal({ station, isFinal });
   };
 
-  const submitLog = (values: { occurredAt: string; note: string }) => {
+  const submitLog = (values: CheckpointModalValues) => {
     if (!logModal) return;
     const { station, isFinal } = logModal;
     recordCheckpoint.mutate(
@@ -272,6 +321,8 @@ export default function TrainScheduleTrackPage() {
           sequenceNo: station.sequenceNo,
           occurredAt: values.occurredAt,
           ...(values.note ? { note: values.note } : {}),
+          // Nothing to clear on a first log — send only what was entered.
+          ...pickHandling(values, false),
         },
       },
       {
@@ -293,13 +344,18 @@ export default function TrainScheduleTrackPage() {
     );
   };
 
-  const submitEdit = (values: { occurredAt: string; note: string }) => {
+  const submitEdit = (values: CheckpointModalValues) => {
     if (!editModal) return;
     updateCheckpoint.mutate(
       {
         id: scheduleId,
         sequenceNo: editModal.sequenceNo,
-        payload: { occurredAt: values.occurredAt, note: values.note || null },
+        payload: {
+          occurredAt: values.occurredAt,
+          note: values.note || null,
+          // Nulls are meaningful here: clearing a picker clears the stamp.
+          ...pickHandling(values, true),
+        },
       },
       {
         onSuccess: () => {
@@ -687,6 +743,11 @@ export default function TrainScheduleTrackPage() {
                 <Text size="xs" c="dimmed">
                   {formatDateTime(cp.occurredAt)}
                 </Text>
+                {handlingHours(cp) !== null ? (
+                  <Text size="xs" c="dimmed" mt={2}>
+                    Loading + unloading {handlingHours(cp)} h
+                  </Text>
+                ) : null}
                 {cp.note ? (
                   <Text size="xs" mt={2}>
                     {cp.note}
@@ -723,9 +784,10 @@ export default function TrainScheduleTrackPage() {
         onClose={() => setEditModal(null)}
         title={`Edit ${editModal?.label ?? "checkpoint"}`}
         icon={<Pencil size={18} />}
-        description="Corrects this leg's time and note only — nothing else changes."
+        description="Corrects this leg's time, station work and note only — nothing else changes."
         initialOccurredAt={editModal?.occurredAt}
         initialNote={editModal?.note}
+        initialHandling={editModal}
         submitLabel="Save"
         loading={updateCheckpoint.isPending}
         onSubmit={submitEdit}