fix: [order] 수주 관리 개선 - stats 상태 추가, 수정 시 item_name 유효성 에러 수정

- stats에 IN_PRODUCTION/PRODUCED 상태 추가
- 수주 수정 시 item_name 유효성 에러 수정 (V1#29)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/Services/OrderService.php

@@ -135,6 +135,8 @@ public function stats(?string $orderType = null): array
             'draft' => $counts[Order::STATUS_DRAFT] ?? 0,
             'confirmed' => $counts[Order::STATUS_CONFIRMED] ?? 0,
             'in_progress' => $counts[Order::STATUS_IN_PROGRESS] ?? 0,
+            'in_production' => $counts[Order::STATUS_IN_PRODUCTION] ?? 0,
+            'produced' => $counts[Order::STATUS_PRODUCED] ?? 0,
             'completed' => $counts[Order::STATUS_COMPLETED] ?? 0,
             'cancelled' => $counts[Order::STATUS_CANCELLED] ?? 0,
             'total_amount' => array_sum($amounts),