feat:문서 resolve/upsert API 추가- React 연동용 resolve API (GET /documents/resolve)

- Upsert API (POST /documents/upsert)
- ResolveRequest, UpsertRequest FormRequest 생성
- DocumentService에 resolve/upsert 로직 추가
- document_category common_codes 마이그레이션
- 에러/성공 메시지 i18n 추가

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

app/Http/Requests/Document/ResolveRequest.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace App\Http\Requests\Document;
+
+use Illuminate\Foundation\Http\FormRequest;
+
+class ResolveRequest extends FormRequest
+{
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    public function rules(): array
+    {
+        return [
+            'category' => 'required|string|max:50',
+            'item_id' => 'required|integer',
+        ];
+    }
+
+    public function messages(): array
+    {
+        return [
+            'category.required' => __('validation.required', ['attribute' => '문서 분류']),
+            'item_id.required' => __('validation.required', ['attribute' => '품목 ID']),
+            'item_id.integer' => __('validation.integer', ['attribute' => '품목 ID']),
+        ];
+    }
+}