refactor(item-master): 독립 엔티티 아키텍처 적용 및 Swagger 보완

- FK 컬럼 제거: item_sections.page_id, item_fields.section_id, item_bom_items.section_id
- entity_relationships 테이블로 전환하여 독립 엔티티 구조 확립
- ItemMasterField 관련 파일 삭제 (Controller, Service, Model, Requests)
- destroy 메서드 독립 엔티티 아키텍처 적용 (관계 링크만 삭제)
- Swagger 스키마에서 FK 참조 제거
- FormRequest 및 Swagger에 group_id(계층번호) 필드 추가

database/migrations/2025_11_27_090523_drop_item_master_fields_table.php

@@ -0,0 +1,31 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Support\Facades\Schema;
+
+/**
+ * item_master_fields 테이블 삭제
+ *
+ * 이유: item_fields로 통합 완료 (2025_11_26_230132 마이그레이션)
+ * - 데이터는 이미 item_fields로 이관됨
+ * - 관련 Model, Service, Controller도 함께 삭제
+ */
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::dropIfExists('item_master_fields');
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        // 테이블 복원이 필요한 경우 2025_11_20_100002 마이그레이션 참조
+        // 데이터는 복원 불가
+    }
+};

database/migrations/2025_11_27_092448_remove_fk_columns_from_item_tables.php

@@ -0,0 +1,156 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Facades\Schema;
+
+/**
+ * FK 컬럼 제거 마이그레이션
+ *
+ * 목적: 모든 엔티티를 완전히 독립적으로 만들고, 관계는 entity_relationships로만 관리
+ *
+ * 제거 대상:
+ * - item_sections.page_id
+ * - item_fields.section_id
+ * - item_bom_items.section_id
+ *
+ * 데이터 이관:
+ * - 기존 FK 데이터는 entity_relationships로 이관 후 컬럼 삭제
+ */
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        // 1. item_sections.page_id → entity_relationships 이관
+        $sections = DB::table('item_sections')
+            ->whereNotNull('page_id')
+            ->whereNull('deleted_at')
+            ->get();
+
+        foreach ($sections as $section) {
+            DB::table('entity_relationships')->insertOrIgnore([
+                'tenant_id' => $section->tenant_id,
+                'group_id' => $section->group_id ?? 1,
+                'parent_type' => 'page',
+                'parent_id' => $section->page_id,
+                'child_type' => 'section',
+                'child_id' => $section->id,
+                'order_no' => $section->order_no ?? 0,
+                'created_at' => now(),
+                'updated_at' => now(),
+            ]);
+        }
+
+        // 2. item_fields.section_id → entity_relationships 이관
+        $fields = DB::table('item_fields')
+            ->whereNotNull('section_id')
+            ->whereNull('deleted_at')
+            ->get();
+
+        foreach ($fields as $field) {
+            DB::table('entity_relationships')->insertOrIgnore([
+                'tenant_id' => $field->tenant_id,
+                'group_id' => $field->group_id ?? 1,
+                'parent_type' => 'section',
+                'parent_id' => $field->section_id,
+                'child_type' => 'field',
+                'child_id' => $field->id,
+                'order_no' => $field->order_no ?? 0,
+                'created_at' => now(),
+                'updated_at' => now(),
+            ]);
+        }
+
+        // 3. item_bom_items.section_id → entity_relationships 이관
+        $bomItems = DB::table('item_bom_items')
+            ->whereNotNull('section_id')
+            ->whereNull('deleted_at')
+            ->get();
+
+        foreach ($bomItems as $bom) {
+            DB::table('entity_relationships')->insertOrIgnore([
+                'tenant_id' => $bom->tenant_id,
+                'group_id' => $bom->group_id ?? 1,
+                'parent_type' => 'section',
+                'parent_id' => $bom->section_id,
+                'child_type' => 'bom',
+                'child_id' => $bom->id,
+                'order_no' => 0,
+                'created_at' => now(),
+                'updated_at' => now(),
+            ]);
+        }
+
+        // 4. FK 컬럼 삭제
+        Schema::table('item_sections', function (Blueprint $table) {
+            $table->dropColumn('page_id');
+        });
+
+        Schema::table('item_fields', function (Blueprint $table) {
+            $table->dropColumn('section_id');
+        });
+
+        Schema::table('item_bom_items', function (Blueprint $table) {
+            $table->dropColumn('section_id');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        // 1. FK 컬럼 복원
+        Schema::table('item_sections', function (Blueprint $table) {
+            $table->unsignedBigInteger('page_id')->nullable()->after('group_id')->comment('페이지 ID');
+        });
+
+        Schema::table('item_fields', function (Blueprint $table) {
+            $table->unsignedBigInteger('section_id')->nullable()->after('group_id')->comment('섹션 ID');
+        });
+
+        Schema::table('item_bom_items', function (Blueprint $table) {
+            $table->unsignedBigInteger('section_id')->nullable()->after('group_id')->comment('섹션 ID');
+        });
+
+        // 2. entity_relationships → FK 복원 (page-section)
+        $pageRelations = DB::table('entity_relationships')
+            ->where('parent_type', 'page')
+            ->where('child_type', 'section')
+            ->get();
+
+        foreach ($pageRelations as $rel) {
+            DB::table('item_sections')
+                ->where('id', $rel->child_id)
+                ->update(['page_id' => $rel->parent_id]);
+        }
+
+        // 3. entity_relationships → FK 복원 (section-field)
+        $fieldRelations = DB::table('entity_relationships')
+            ->where('parent_type', 'section')
+            ->where('child_type', 'field')
+            ->get();
+
+        foreach ($fieldRelations as $rel) {
+            DB::table('item_fields')
+                ->where('id', $rel->child_id)
+                ->update(['section_id' => $rel->parent_id]);
+        }
+
+        // 4. entity_relationships → FK 복원 (section-bom)
+        $bomRelations = DB::table('entity_relationships')
+            ->where('parent_type', 'section')
+            ->where('child_type', 'bom')
+            ->get();
+
+        foreach ($bomRelations as $rel) {
+            DB::table('item_bom_items')
+                ->where('id', $rel->child_id)
+                ->update(['section_id' => $rel->parent_id]);
+        }
+    }
+};