fix(rule-engine): merge duplicate Sebeta yards, block dupes

Two active Sebeta yards (LEGACY_DEST/'Sebeta' and SEBETA/'sebeta')
split rates and routes across different yard ids, so route-scoped rate
lookups missed. Migration repoints every yard reference to the survivor,
retires the duplicate, and adds partial unique indexes on active label
and code. Service now rejects case-insensitive duplicate labels on
create/update - the old guard only compared generated codes, which
missed labels whose existing code differs (LEGACY_DEST).

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

apps/edr-freight-api/src/modules/rule-engine/repositories/yards.repository.ts

@@ -22,6 +22,15 @@ export class YardsRepository implements IYardsRepository {
     return this.repo.findOne({ where: { code } });
   }
 
+  /** Case/whitespace-insensitive label lookup — backs the duplicate-yard guard. */
+  findByLabelInsensitive(label: string): Promise<Yard | null> {
+    return this.repo
+      .createQueryBuilder('yard')
+      .where('LOWER(TRIM(yard.label)) = LOWER(TRIM(:label))', { label })
+      .andWhere('yard.deleted_at IS NULL')
+      .getOne();
+  }
+
   findAll(options?: FindManyOptions<Yard>): Promise<Yard[]> {
     return this.repo.find(options);
   }