fix: API 응답 파싱 오류 수정 및 에러 처리 개선

주요 변경사항:
- 창고 관리 API 응답 구조와 DTO 불일치 수정
  - WarehouseLocationDto에 code, manager_phone 필드 추가
  - RemoteDataSource에서 API 응답을 DTO 구조에 맞게 변환
- 회사 관리 API 응답 파싱 오류 수정
  - CompanyResponse의 필수 필드를 nullable로 변경
  - PaginatedResponse 구조 매핑 로직 개선
- 에러 처리 및 로깅 개선
  - Service Layer에 상세 에러 로깅 추가
  - Controller에서 에러 타입별 처리
- 새로운 유틸리티 추가
  - ResponseInterceptor: API 응답 정규화
  - DebugLogger: 디버깅 도구
  - HealthCheckService: 서버 상태 확인
- 문서화
  - API 통합 테스트 가이드
  - 에러 분석 보고서
  - 리팩토링 계획서

lib/data/models/auth/login_request.freezed.dart

@@ -20,7 +20,8 @@ LoginRequest _$LoginRequestFromJson(Map<String, dynamic> json) {
 
 /// @nodoc
 mixin _$LoginRequest {
-  String get email => throw _privateConstructorUsedError;
+  String? get username => throw _privateConstructorUsedError;
+  String? get email => throw _privateConstructorUsedError;
   String get password => throw _privateConstructorUsedError;
 
   /// Serializes this LoginRequest to a JSON map.
@@ -39,7 +40,7 @@ abstract class $LoginRequestCopyWith<$Res> {
           LoginRequest value, $Res Function(LoginRequest) then) =
       _$LoginRequestCopyWithImpl<$Res, LoginRequest>;
   @useResult
-  $Res call({String email, String password});
+  $Res call({String? username, String? email, String password});
 }
 
 /// @nodoc
@@ -57,14 +58,19 @@ class _$LoginRequestCopyWithImpl<$Res, $Val extends LoginRequest>
   @pragma('vm:prefer-inline')
   @override
   $Res call({
-    Object? email = null,
+    Object? username = freezed,
+    Object? email = freezed,
     Object? password = null,
   }) {
     return _then(_value.copyWith(
-      email: null == email
+      username: freezed == username
+          ? _value.username
+          : username // ignore: cast_nullable_to_non_nullable
+              as String?,
+      email: freezed == email
           ? _value.email
           : email // ignore: cast_nullable_to_non_nullable
-              as String,
+              as String?,
       password: null == password
           ? _value.password
           : password // ignore: cast_nullable_to_non_nullable
@@ -81,7 +87,7 @@ abstract class _$$LoginRequestImplCopyWith<$Res>
       __$$LoginRequestImplCopyWithImpl<$Res>;
   @override
   @useResult
-  $Res call({String email, String password});
+  $Res call({String? username, String? email, String password});
 }
 
 /// @nodoc
@@ -97,14 +103,19 @@ class __$$LoginRequestImplCopyWithImpl<$Res>
   @pragma('vm:prefer-inline')
   @override
   $Res call({
-    Object? email = null,
+    Object? username = freezed,
+    Object? email = freezed,
     Object? password = null,
   }) {
     return _then(_$LoginRequestImpl(
-      email: null == email
+      username: freezed == username
+          ? _value.username
+          : username // ignore: cast_nullable_to_non_nullable
+              as String?,
+      email: freezed == email
           ? _value.email
           : email // ignore: cast_nullable_to_non_nullable
-              as String,
+              as String?,
       password: null == password
           ? _value.password
           : password // ignore: cast_nullable_to_non_nullable
@@ -116,19 +127,21 @@ class __$$LoginRequestImplCopyWithImpl<$Res>
 /// @nodoc
 @JsonSerializable()
 class _$LoginRequestImpl implements _LoginRequest {
-  const _$LoginRequestImpl({required this.email, required this.password});
+  const _$LoginRequestImpl({this.username, this.email, required this.password});
 
   factory _$LoginRequestImpl.fromJson(Map<String, dynamic> json) =>
       _$$LoginRequestImplFromJson(json);
 
   @override
-  final String email;
+  final String? username;
+  @override
+  final String? email;
   @override
   final String password;
 
   @override
   String toString() {
-    return 'LoginRequest(email: $email, password: $password)';
+    return 'LoginRequest(username: $username, email: $email, password: $password)';
   }
 
   @override
@@ -136,6 +149,8 @@ class _$LoginRequestImpl implements _LoginRequest {
     return identical(this, other) ||
         (other.runtimeType == runtimeType &&
             other is _$LoginRequestImpl &&
+            (identical(other.username, username) ||
+                other.username == username) &&
             (identical(other.email, email) || other.email == email) &&
             (identical(other.password, password) ||
                 other.password == password));
@@ -143,7 +158,7 @@ class _$LoginRequestImpl implements _LoginRequest {
 
   @JsonKey(includeFromJson: false, includeToJson: false)
   @override
-  int get hashCode => Object.hash(runtimeType, email, password);
+  int get hashCode => Object.hash(runtimeType, username, email, password);
 
   /// Create a copy of LoginRequest
   /// with the given fields replaced by the non-null parameter values.
@@ -163,14 +178,17 @@ class _$LoginRequestImpl implements _LoginRequest {
 
 abstract class _LoginRequest implements LoginRequest {
   const factory _LoginRequest(
-      {required final String email,
+      {final String? username,
+      final String? email,
       required final String password}) = _$LoginRequestImpl;
 
   factory _LoginRequest.fromJson(Map<String, dynamic> json) =
       _$LoginRequestImpl.fromJson;
 
   @override
-  String get email;
+  String? get username;
+  @override
+  String? get email;
   @override
   String get password;