feat:문서 템플릿 기본필드 field_key 연동키 드롭다운 추가

- DocumentTemplateController: common_codes(doc_template_basic_field) 조회하여 뷰에 전달
- prepareTemplateData: basic_fields에 field_key 포함
- DocumentTemplateApiController: basic_fields 저장 시 field_key 포함
- edit.blade.php: 기본필드 행에 '연동키 선택' 드롭다운 추가

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

app/Http/Controllers/Api/Admin/DocumentTemplateApiController.php

@@ -593,6 +593,7 @@ private function saveRelations(DocumentTemplate $template, array $data, bool $de
                 DocumentTemplateBasicField::create([
                     'template_id' => $template->id,
                     'label' => $field['label'] ?? '',
+                    'field_key' => $field['field_key'] ?? null,
                     'field_type' => $field['field_type'] ?? 'text',
                     'default_value' => $field['default_value'] ?? '',
                     'sort_order' => $index,

app/Http/Controllers/DocumentTemplateController.php

@@ -4,6 +4,7 @@
 
 use App\Models\DocumentTemplate;
 use App\Models\DocumentTemplateFieldPreset;
+use App\Models\Products\CommonCode;
 use App\Models\Tenants\Tenant;
 use App\Models\User;
 use Illuminate\Http\Request;
@@ -39,6 +40,7 @@ public function create(): View
             'categories' => $this->getCategories(),
             'tenant' => $this->getCurrentTenant(),
             'presets' => DocumentTemplateFieldPreset::orderBy('sort_order')->get(),
+            'basicFieldKeys' => $this->getBasicFieldKeys(),
         ]);
     }
 
@@ -66,6 +68,7 @@ public function edit(int $id): View
             'categories' => $this->getCategories(),
             'tenant' => $this->getCurrentTenant(),
             'presets' => DocumentTemplateFieldPreset::orderBy('sort_order')->get(),
+            'basicFieldKeys' => $this->getBasicFieldKeys(),
         ]);
     }
 
@@ -79,6 +82,19 @@ private function getCurrentTenant(): ?Tenant
         return $tenantId ? Tenant::find($tenantId) : null;
     }
 
+    /**
+     * 기본필드 키 옵션 조회 (common_codes 기반)
+     */
+    private function getBasicFieldKeys(): array
+    {
+        return CommonCode::query()
+            ->where('code_group', 'doc_template_basic_field')
+            ->where('is_active', true)
+            ->orderBy('sort_order')
+            ->get(['code', 'name'])
+            ->toArray();
+    }
+
     /**
      * 문서분류 목록 조회 (common_codes 기반 + 기존 데이터 폴백)
      */
@@ -167,6 +183,7 @@ private function prepareTemplateData(DocumentTemplate $template): array
                 return [
                     'id' => $f->id,
                     'label' => $f->label,
+                    'field_key' => $f->field_key,
                     'field_type' => $f->field_type,
                     'default_value' => $f->default_value,
                 ];