refactor: 회사 폼 UI 개선 및 코드 정리

- 담당자 연락처 필드를 드롭다운 + 입력 방식으로 분리
- 사용자 폼과 동일한 전화번호 UI 패턴 적용
- 미사용 위젯 파일 4개 정리 (branch_card, contact_info_* 등)
- 파일명 통일성 확보 (branch_edit_screen → branch_form, company_form_simplified → company_form)
- 네이밍 일관성 개선으로 유지보수성 향상

lib/data/models/company/company_dto.g.dart

@@ -51,6 +51,8 @@ _$UpdateCompanyRequestImpl _$$UpdateCompanyRequestImplFromJson(
       companyTypes: (json['company_types'] as List<dynamic>?)
           ?.map((e) => e as String)
           .toList(),
+      isPartner: json['is_partner'] as bool?,
+      isCustomer: json['is_customer'] as bool?,
       remark: json['remark'] as String?,
       isActive: json['is_active'] as bool?,
     );
@@ -65,6 +67,8 @@ Map<String, dynamic> _$$UpdateCompanyRequestImplToJson(
       'contact_phone': instance.contactPhone,
       'contact_email': instance.contactEmail,
       'company_types': instance.companyTypes,
+      'is_partner': instance.isPartner,
+      'is_customer': instance.isCustomer,
       'remark': instance.remark,
       'is_active': instance.isActive,
     };
@@ -74,7 +78,7 @@ _$CompanyResponseImpl _$$CompanyResponseImplFromJson(
     _$CompanyResponseImpl(
       id: (json['id'] as num).toInt(),
       name: json['name'] as String,
-      address: json['address'] as String,
+      address: json['address'] as String?,
       contactName: json['contact_name'] as String,
       contactPosition: json['contact_position'] as String?,
       contactPhone: json['contact_phone'] as String,