feat: [생산지시] 전용 API 엔드포인트 신규 생성

- ProductionOrderService: 목록(index), 통계(stats), 상세(show) 구현
  - Order 기반 생산지시 대상 필터링 (IN_PROGRESS~SHIPPED)
  - workOrderProgress 가공 필드 (total/completed/inProgress)
  - production_ordered_at (첫 WorkOrder created_at 기반)
  - BOM 공정 분류 추출 (order_nodes.options.bom_result)
- ProductionOrderController: FormRequest + ApiResponse 패턴
- ProductionOrderIndexRequest: search, production_status, sort, pagination 검증
- ProductionOrderApi.php: Swagger 문서 (목록/통계/상세)
- production.php: GET /production-orders, /stats, /{orderId} 라우트 추가

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/Http/Requests/ProductionOrder/ProductionOrderIndexRequest.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace App\Http\Requests\ProductionOrder;
+
+use Illuminate\Foundation\Http\FormRequest;
+
+class ProductionOrderIndexRequest extends FormRequest
+{
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    public function rules(): array
+    {
+        return [
+            'search' => 'nullable|string|max:100',
+            'production_status' => 'nullable|in:waiting,in_production,completed',
+            'sort_by' => 'nullable|in:created_at,delivery_date,order_no',
+            'sort_dir' => 'nullable|in:asc,desc',
+            'page' => 'nullable|integer|min:1',
+            'per_page' => 'nullable|integer|min:1|max:100',
+        ];
+    }
+}