feat: 사용자 관리 시스템 백엔드 API 호환성 대폭 개선

- UserRemoteDataSource: API v0.2.1 스펙 완전 대응
  • 응답 형식 통일 (success: true 구조)
  • 페이지네이션 처리 개선
  • 에러 핸들링 강화
  • 불필요한 파라미터 제거 (includeInactive 등)

- UserDto 모델 현대화:
  • 서버 응답 구조와 100% 일치
  • 도메인 모델 변환 메서드 추가
  • Freezed 불변성 패턴 완성

- User 도메인 모델 신규 구현:
  • Clean Architecture 원칙 준수
  • UserRole enum 타입 안전성 강화
  • 비즈니스 로직 캡슐화

- 사용자 관련 UseCase 리팩토링:
  • Repository 패턴 완전 적용
  • Either<Failure, Success> 에러 처리
  • 의존성 주입 최적화

- UI 컨트롤러 및 화면 개선:
  • API 응답 변경사항 반영
  • 사용자 권한 표시 정확성 향상
  • 폼 검증 로직 강화

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

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

lib/data/models/user/user_dto.g.dart

@@ -11,19 +11,14 @@ _$UserDtoImpl _$$UserDtoImplFromJson(Map<String, dynamic> json) =>
       id: (json['id'] as num).toInt(),
       username: json['username'] as String,
       name: json['name'] as String,
-      email: json['email'] as String?,
+      email: json['email'] as String,
       phone: json['phone'] as String?,
       role: json['role'] as String,
-      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?,
       isActive: json['is_active'] as bool,
-      lastLoginAt: json['last_login_at'] == null
-          ? null
-          : DateTime.parse(json['last_login_at'] as String),
       createdAt: DateTime.parse(json['created_at'] as String),
-      updatedAt: DateTime.parse(json['updated_at'] as String),
+      updatedAt: json['updated_at'] == null
+          ? null
+          : DateTime.parse(json['updated_at'] as String),
     );
 
 Map<String, dynamic> _$$UserDtoImplToJson(_$UserDtoImpl instance) =>
@@ -34,27 +29,20 @@ Map<String, dynamic> _$$UserDtoImplToJson(_$UserDtoImpl instance) =>
       'email': instance.email,
       'phone': instance.phone,
       'role': instance.role,
-      'company_id': instance.companyId,
-      'company_name': instance.companyName,
-      'branch_id': instance.branchId,
-      'branch_name': instance.branchName,
       'is_active': instance.isActive,
-      'last_login_at': instance.lastLoginAt?.toIso8601String(),
       'created_at': instance.createdAt.toIso8601String(),
-      'updated_at': instance.updatedAt.toIso8601String(),
+      'updated_at': instance.updatedAt?.toIso8601String(),
     };
 
 _$CreateUserRequestImpl _$$CreateUserRequestImplFromJson(
         Map<String, dynamic> json) =>
     _$CreateUserRequestImpl(
       username: json['username'] as String,
-      email: json['email'] as String?,
+      email: json['email'] as String,
       password: json['password'] as String,
       name: json['name'] as String,
       phone: json['phone'] as String?,
       role: json['role'] as String,
-      companyId: (json['company_id'] as num?)?.toInt(),
-      branchId: (json['branch_id'] as num?)?.toInt(),
     );
 
 Map<String, dynamic> _$$CreateUserRequestImplToJson(
@@ -66,8 +54,6 @@ Map<String, dynamic> _$$CreateUserRequestImplToJson(
       'name': instance.name,
       'phone': instance.phone,
       'role': instance.role,
-      'company_id': instance.companyId,
-      'branch_id': instance.branchId,
     };
 
 _$UpdateUserRequestImpl _$$UpdateUserRequestImplFromJson(
@@ -78,9 +64,6 @@ _$UpdateUserRequestImpl _$$UpdateUserRequestImplFromJson(
       password: json['password'] as String?,
       phone: json['phone'] as String?,
       role: json['role'] as String?,
-      companyId: (json['company_id'] as num?)?.toInt(),
-      branchId: (json['branch_id'] as num?)?.toInt(),
-      isActive: json['is_active'] as bool?,
     );
 
 Map<String, dynamic> _$$UpdateUserRequestImplToJson(
@@ -91,35 +74,20 @@ Map<String, dynamic> _$$UpdateUserRequestImplToJson(
       'password': instance.password,
       'phone': instance.phone,
       'role': instance.role,
-      'company_id': instance.companyId,
-      'branch_id': instance.branchId,
-      'is_active': instance.isActive,
     };
 
-_$ChangeStatusRequestImpl _$$ChangeStatusRequestImplFromJson(
+_$CheckUsernameResponseImpl _$$CheckUsernameResponseImplFromJson(
         Map<String, dynamic> json) =>
-    _$ChangeStatusRequestImpl(
-      isActive: json['is_active'] as bool,
+    _$CheckUsernameResponseImpl(
+      available: json['available'] as bool,
+      message: json['message'] as String?,
     );
 
-Map<String, dynamic> _$$ChangeStatusRequestImplToJson(
-        _$ChangeStatusRequestImpl instance) =>
+Map<String, dynamic> _$$CheckUsernameResponseImplToJson(
+        _$CheckUsernameResponseImpl instance) =>
     <String, dynamic>{
-      'is_active': instance.isActive,
-    };
-
-_$ChangePasswordRequestImpl _$$ChangePasswordRequestImplFromJson(
-        Map<String, dynamic> json) =>
-    _$ChangePasswordRequestImpl(
-      currentPassword: json['current_password'] as String,
-      newPassword: json['new_password'] as String,
-    );
-
-Map<String, dynamic> _$$ChangePasswordRequestImplToJson(
-        _$ChangePasswordRequestImpl instance) =>
-    <String, dynamic>{
-      'current_password': instance.currentPassword,
-      'new_password': instance.newPassword,
+      'available': instance.available,
+      'message': instance.message,
     };
 
 _$UserListDtoImpl _$$UserListDtoImplFromJson(Map<String, dynamic> json) =>