Add migration to widen window_duration_hours precision and update related components for duration handling

apps/edr-freight-api/src/modules/train-scheduling/entities/train-scheduling-global-rules.entity.ts

@@ -54,11 +54,13 @@ export class TrainSchedulingGlobalRules extends BaseEntity {
   @Column({ name: 'window_open_hour', type: 'int', default: 8 })
   windowOpenHour!: number;
 
+  // Stored in hours; 4 decimals so sub-minute UI durations (4 min = 0.0667h)
+  // are exact. See WidenWindowDurationHoursPrecision migration.
   @Column({
     name: 'window_duration_hours',
     type: 'numeric',
-    precision: 4,
-    scale: 2,
+    precision: 6,
+    scale: 4,
     default: 3,
   })
   windowDurationHours!: number;