feat: 회사 관리 기능 개선 및 지점 평면화 DTO 추가

- CompanyBranchFlatDto 모델 추가로 지점 데이터 처리 개선
- 회사 서비스에 브랜치 평면화 기능 추가
- 회사 폼 컨트롤러 기능 확장
- 회사 리스트 화면 UI 개선

🤖 Generated with [Claude Code](https://claude.ai/code)

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

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

@@ -0,0 +1,25 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'company_branch_flat_dto.dart';
+
+// **************************************************************************
+// JsonSerializableGenerator
+// **************************************************************************
+
+_$CompanyBranchFlatDtoImpl _$$CompanyBranchFlatDtoImplFromJson(
+        Map<String, dynamic> json) =>
+    _$CompanyBranchFlatDtoImpl(
+      companyId: (json['company_id'] as num).toInt(),
+      companyName: json['company_name'] as String,
+      branchId: (json['branch_id'] as num?)?.toInt(),
+      branchName: json['branch_name'] as String?,
+    );
+
+Map<String, dynamic> _$$CompanyBranchFlatDtoImplToJson(
+        _$CompanyBranchFlatDtoImpl instance) =>
+    <String, dynamic>{
+      'company_id': instance.companyId,
+      'company_name': instance.companyName,
+      'branch_id': instance.branchId,
+      'branch_name': instance.branchName,
+    };