feat(train): enhance train history and scheduling features

- Added a reason field to train history entries for detach/maintenance actions.
- Updated TrainHistoryPanel to display the reason for wagon detachments.
- Introduced per-wagon load/unload functionality in ScheduleWorkspacePanel with a modal for managing individual wagons.
- Implemented API endpoints for loading and unloading specific wagons, including the ability to cancel remaining wagons with a reason.
- Refactored detach request handling in TrainBuilderDetailPage to streamline the process and remove the approval flow, requiring a reason for detachments.
- Updated types and services to support new wagon loading/unloading features and booking wagon retrieval.

apps/edr-freight-api/src/modules/train-scheduling/services/train-scheduling.service.ts

@@ -2946,6 +2946,10 @@ export class TrainSchedulingService {
     // The yard plan this departure was SOLD against must match where the steel
     // actually stands: a wagon sold from Dire but still in Mojo cannot board.
     await this.assertPlannedYardsAligned(schedule);
+    // Per-wagon loading: a booking mid-load is neither ridable nor removable —
+    // every wagon must be LOADED, or the never-loaded remainder cancelled
+    // (at-loading cancellation), before the train departs.
+    await this.assertNoPartiallyLoadedBookings(schedule);
 
     await this.dataSource.transaction(async (manager) => {
       const trainNumber = await this.assignTrainNumber(manager, schedule);
@@ -3144,6 +3148,42 @@ export class TrainSchedulingService {
    * PAID — or FULLY_EXECUTED for shipping-line bookings, which never prepay
    * (their charge sits on the credit ledger) yet ride from accept.
    */
+  /**
+   * Per-wagon loading dispatch gate: a booking with SOME wagons LOADED and
+   * SOME still PLANNED/RESERVED must resolve before departure — load the rest
+   * or cancel it (which shrinks the booking to its loaded wagons). Blocking
+   * here beats silently unassigning: unassign would delete LOADED allocations
+   * and strand cargo that is physically on the train.
+   */
+  private async assertNoPartiallyLoadedBookings(schedule: TrainSchedule): Promise<void> {
+    if (!schedule.trainSetId) return;
+    const rows: Array<{ reference: string; loaded: string; total: string }> =
+      await this.dataSource.query(
+        `SELECT b.reference,
+                COUNT(*) FILTER (WHERE a.status IN ('LOADED', 'DEPARTED')) AS loaded,
+                COUNT(*) AS total
+           FROM freight.wagon_booking_allocations a
+           JOIN freight.train_set_wagons tsw ON tsw.id = a.train_set_wagon_id
+           JOIN freight.bookings b ON b.id = a.booking_id
+          WHERE tsw.train_set_id = $1
+            AND a.deleted_at IS NULL
+            AND tsw.deleted_at IS NULL
+            AND b.deleted_at IS NULL
+          GROUP BY b.id, b.reference
+         HAVING COUNT(*) FILTER (WHERE a.status IN ('LOADED', 'DEPARTED')) > 0
+            AND COUNT(*) FILTER (WHERE a.status NOT IN ('LOADED', 'DEPARTED')) > 0`,
+        [schedule.trainSetId],
+      );
+    if (rows.length) {
+      const detail = rows
+        .map((r) => `${r.reference} (${r.loaded}/${r.total} wagons loaded)`)
+        .join(', ');
+      throw new BadRequestException(
+        `Cannot dispatch: booking(s) partially loaded — load every wagon or cancel the remainder first: ${detail}`,
+      );
+    }
+  }
+
   private async unloadedOriginBoarderIds(
     scheduleId: string,
     originYardId: string,
@@ -3157,6 +3197,7 @@ export class TrainSchedulingService {
           AND b.deleted_at IS NULL
           AND b.origin_yard_id = $2
           AND b.loaded_at IS NULL
+          AND b.loading_started_at IS NULL
           AND COALESCE(tsb.loading_status, 'UNLOADED') <> 'LOADED'
           AND b.is_government = false
           AND (b.status = 'PAID'