feat(train-scheduling): mid-route consist changes, audit history, safer workspace

- planned couples: loose wagons join the train at a route stop, added
  from the schedule yards tab; capacity credits them per corridor edge
  and coupling validates locomotive weight/length caps per leg
- real-cut toggle: a cut wagon permanently leaves the train build at
  its cut yard (soft cut still sits out one trip only)
- fix heaviest-leg display counting a shared slot's full cargo on
  every spanned edge (phantom pull-weight overload on S-2026-00045)
- confirmation dialogs for workspace add/load/unload/remove actions
- train-builder History and Detached-wagons tabs, backed by paginated
  endpoints; builder detaches now always write adjustment-log rows

Migrations 3660 (planned_wagon_couples, planned_wagon_real_cuts) and
3670 (adjustment log train_schedule_id nullable) — both applied to the
dev DB by hand; watch mode does not run migrations.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/edr-freight-web/backoffice/src/pages/trainBuilder/TrainBuilderDetailPage.tsx

@@ -9,6 +9,7 @@ import {
   Modal,
   Progress,
   Stack,
+  Tabs,
   Text,
   Textarea,
 } from "@mantine/core";
@@ -17,8 +18,10 @@ import { isAxiosError } from "axios";
 import {
   AlertTriangle,
   CalendarClock,
+  History,
   MapPin,
   MoreHorizontal,
+  PackageOpen,
   Power,
   PowerOff,
   Replace,
@@ -36,6 +39,8 @@ import AvailableWagonsPanel from "@/components/trainBuilder/AvailableWagonsPanel
 import ChangeLocomotivesModal from "@/components/trainBuilder/ChangeLocomotivesModal";
 import ChangeYardModal from "@/components/trainBuilder/ChangeYardModal";
 import ConsistWagonList from "@/components/trainBuilder/ConsistWagonList";
+import DetachedWagonsPanel from "@/components/trainBuilder/DetachedWagonsPanel";
+import TrainHistoryPanel from "@/components/trainBuilder/TrainHistoryPanel";
 import {
   directionColor,
   locomotiveStatusColor,
@@ -383,7 +388,22 @@ export default function TrainBuilderDetailPage() {
         ]}
       />
 
-      {composition.wagonYards.length > 1 ? (
+      <Tabs defaultValue="build" keepMounted={false}>
+        <Tabs.List>
+          <Tabs.Tab value="build" leftSection={<TrainIcon size={14} />}>
+            Build
+          </Tabs.Tab>
+          <Tabs.Tab value="detached" leftSection={<PackageOpen size={14} />}>
+            Detached wagons
+          </Tabs.Tab>
+          <Tabs.Tab value="history" leftSection={<History size={14} />}>
+            History
+          </Tabs.Tab>
+        </Tabs.List>
+
+        <Tabs.Panel value="build" pt="md">
+          <Stack gap="lg">
+            {composition.wagonYards.length > 1 ? (
         <Alert color="blue" icon={<MapPin size={16} />}>
           <Stack gap={4}>
             <Text size="sm" fw={600}>
@@ -575,6 +595,22 @@ export default function TrainBuilderDetailPage() {
           </Stack>
         </Card>
       ) : null}
+          </Stack>
+        </Tabs.Panel>
+
+        <Tabs.Panel value="detached" pt="md">
+          <DetachedWagonsPanel
+            trainId={composition.id}
+            canAttach={composition.editable && canAssign}
+            attachPending={assignWagons.isPending}
+            onAttach={handleAssign}
+          />
+        </Tabs.Panel>
+
+        <Tabs.Panel value="history" pt="md">
+          <TrainHistoryPanel trainId={composition.id} />
+        </Tabs.Panel>
+      </Tabs>
 
       <ChangeLocomotivesModal
         composition={composition}