feat: Item Master 하이브리드 구조 전환 및 독립 API 추가

- CASCADE FK → 독립 엔티티 + entity_relationships 링크 테이블
- 독립 API 10개 추가 (섹션/필드/BOM CRUD, clone, usage)
- SectionTemplate 모델 제거 → ItemSection.is_template 통합
- 페이지-섹션, 섹션-필드, 섹션-BOM 링크/언링크 API 14개 추가
- Swagger 문서 업데이트

app/Services/ItemMaster/ItemSectionService.php

@@ -2,12 +2,172 @@
 
 namespace App\Services\ItemMaster;
 
+use App\Models\ItemMaster\EntityRelationship;
+use App\Models\ItemMaster\ItemBomItem;
+use App\Models\ItemMaster\ItemField;
 use App\Models\ItemMaster\ItemSection;
 use App\Services\Service;
+use Illuminate\Database\Eloquent\Collection;
 use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
 
 class ItemSectionService extends Service
 {
+    /**
+     * 독립 섹션 목록 조회
+     *
+     * GET /api/v1/item-master/sections
+     */
+    public function index(?bool $isTemplate = null): Collection
+    {
+        $tenantId = $this->tenantId();
+
+        $query = ItemSection::where('tenant_id', $tenantId)
+            ->with(['fields', 'bomItems']);
+
+        if ($isTemplate === true) {
+            $query->templates();
+        } elseif ($isTemplate === false) {
+            $query->nonTemplates();
+        }
+
+        return $query->orderBy('created_at', 'desc')->get();
+    }
+
+    /**
+     * 독립 섹션 생성 (페이지 연결 없음)
+     *
+     * POST /api/v1/item-master/sections
+     */
+    public function storeIndependent(array $data): ItemSection
+    {
+        $tenantId = $this->tenantId();
+        $userId = $this->apiUserId();
+
+        $section = ItemSection::create([
+            'tenant_id' => $tenantId,
+            'group_id' => $data['group_id'] ?? 1,
+            'page_id' => null,
+            'title' => $data['title'],
+            'type' => $data['type'],
+            'order_no' => 0,
+            'is_template' => $data['is_template'] ?? false,
+            'is_default' => $data['is_default'] ?? false,
+            'description' => $data['description'] ?? null,
+            'created_by' => $userId,
+        ]);
+
+        return $section->load(['fields', 'bomItems']);
+    }
+
+    /**
+     * 섹션 복제
+     *
+     * POST /api/v1/item-master/sections/{id}/clone
+     */
+    public function clone(int $id): ItemSection
+    {
+        $tenantId = $this->tenantId();
+        $userId = $this->apiUserId();
+
+        $original = ItemSection::where('tenant_id', $tenantId)
+            ->where('id', $id)
+            ->with(['fields', 'bomItems'])
+            ->first();
+
+        if (! $original) {
+            throw new NotFoundHttpException(__('error.section_not_found'));
+        }
+
+        // 섹션 복제
+        $cloned = ItemSection::create([
+            'tenant_id' => $tenantId,
+            'group_id' => $original->group_id,
+            'page_id' => null,
+            'title' => $original->title.' (복사본)',
+            'type' => $original->type,
+            'order_no' => 0,
+            'is_template' => $original->is_template,
+            'is_default' => false,
+            'description' => $original->description,
+            'created_by' => $userId,
+        ]);
+
+        // 필드 복제
+        foreach ($original->fields as $field) {
+            ItemField::create([
+                'tenant_id' => $tenantId,
+                'group_id' => $field->group_id,
+                'section_id' => $cloned->id,
+                'field_name' => $field->field_name,
+                'field_type' => $field->field_type,
+                'order_no' => $field->order_no,
+                'is_required' => $field->is_required,
+                'default_value' => $field->default_value,
+                'placeholder' => $field->placeholder,
+                'display_condition' => $field->display_condition,
+                'validation_rules' => $field->validation_rules,
+                'options' => $field->options,
+                'properties' => $field->properties,
+                'created_by' => $userId,
+            ]);
+        }
+
+        // BOM 항목 복제
+        foreach ($original->bomItems as $bom) {
+            ItemBomItem::create([
+                'tenant_id' => $tenantId,
+                'group_id' => $bom->group_id,
+                'section_id' => $cloned->id,
+                'item_code' => $bom->item_code,
+                'item_name' => $bom->item_name,
+                'quantity' => $bom->quantity,
+                'unit' => $bom->unit,
+                'unit_price' => $bom->unit_price,
+                'total_price' => $bom->total_price,
+                'spec' => $bom->spec,
+                'note' => $bom->note,
+                'created_by' => $userId,
+            ]);
+        }
+
+        return $cloned->load(['fields', 'bomItems']);
+    }
+
+    /**
+     * 섹션 사용처 조회 (어떤 페이지에 연결되어 있는지)
+     *
+     * GET /api/v1/item-master/sections/{id}/usage
+     */
+    public function getUsage(int $id): array
+    {
+        $tenantId = $this->tenantId();
+
+        $section = ItemSection::where('tenant_id', $tenantId)
+            ->where('id', $id)
+            ->first();
+
+        if (! $section) {
+            throw new NotFoundHttpException(__('error.section_not_found'));
+        }
+
+        // 1. 기존 FK 기반 연결 (page_id)
+        $directPage = $section->page;
+
+        // 2. entity_relationships 기반 연결
+        $linkedPageIds = EntityRelationship::where('child_type', EntityRelationship::TYPE_SECTION)
+            ->where('child_id', $id)
+            ->where('parent_type', EntityRelationship::TYPE_PAGE)
+            ->pluck('parent_id')
+            ->toArray();
+
+        return [
+            'section_id' => $id,
+            'direct_page' => $directPage,
+            'linked_pages' => $section->linkedPages()->get(),
+            'total_usage_count' => ($directPage ? 1 : 0) + count($linkedPageIds),
+        ];
+    }
+
     /**
      * 섹션 생성
      */