feat: 수주관리(Order Management) API Phase 1.1 구현

- OrderService 구현 (index, stats, show, store, update, destroy, updateStatus)
- OrderController 구현 (7개 API 엔드포인트)
- FormRequest 클래스 3개 생성 (Store, Update, UpdateStatus)
- 상태 전환 규칙 검증 (DRAFT → CONFIRMED → IN_PROGRESS → COMPLETED/CANCELLED)
- 수주번호 자동 생성 (ORD{YYYYMMDD}{0001} 형식)
- Swagger API 문서 작성 (OrderApi.php)
- i18n 메시지 키 추가 (ko/en)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/Http/Requests/Order/UpdateOrderStatusRequest.php

@@ -0,0 +1,36 @@
+<?php
+
+namespace App\Http\Requests\Order;
+
+use App\Models\Orders\Order;
+use Illuminate\Foundation\Http\FormRequest;
+use Illuminate\Validation\Rule;
+
+class UpdateOrderStatusRequest extends FormRequest
+{
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    public function rules(): array
+    {
+        return [
+            'status' => ['required', Rule::in([
+                Order::STATUS_DRAFT,
+                Order::STATUS_CONFIRMED,
+                Order::STATUS_IN_PROGRESS,
+                Order::STATUS_COMPLETED,
+                Order::STATUS_CANCELLED,
+            ])],
+        ];
+    }
+
+    public function messages(): array
+    {
+        return [
+            'status.required' => __('validation.required', ['attribute' => '상태']),
+            'status.in' => __('validation.in', ['attribute' => '상태']),
+        ];
+    }
+}