feat: API 인증 시스템 구현 및 로그인 화면 연동

- AuthService, AuthRemoteDataSource 구현
- JWT 토큰 관리 (SecureStorage 사용)
- 로그인 화면 API 연동 및 에러 처리
- freezed 패키지로 Auth 관련 DTO 모델 생성
- 의존성 주입 설정 업데이트

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

@@ -0,0 +1,183 @@
+// coverage:ignore-file
+// GENERATED CODE - DO NOT MODIFY BY HAND
+// ignore_for_file: type=lint
+// ignore_for_file: unused_element, deprecated_member_use, deprecated_member_use_from_same_package, use_function_type_syntax_for_parameters, unnecessary_const, avoid_init_to_null, invalid_override_different_default_values_named, prefer_expression_function_bodies, annotate_overrides, invalid_annotation_target, unnecessary_question_mark
+
+part of 'login_request.dart';
+
+// **************************************************************************
+// FreezedGenerator
+// **************************************************************************
+
+T _$identity<T>(T value) => value;
+
+final _privateConstructorUsedError = UnsupportedError(
+    'It seems like you constructed your class using `MyClass._()`. This constructor is only meant to be used by freezed and you are not supposed to need it nor use it.\nPlease check the documentation here for more information: https://github.com/rrousselGit/freezed#adding-getters-and-methods-to-our-models');
+
+LoginRequest _$LoginRequestFromJson(Map<String, dynamic> json) {
+  return _LoginRequest.fromJson(json);
+}
+
+/// @nodoc
+mixin _$LoginRequest {
+  String get email => throw _privateConstructorUsedError;
+  String get password => throw _privateConstructorUsedError;
+
+  /// Serializes this LoginRequest to a JSON map.
+  Map<String, dynamic> toJson() => throw _privateConstructorUsedError;
+
+  /// Create a copy of LoginRequest
+  /// with the given fields replaced by the non-null parameter values.
+  @JsonKey(includeFromJson: false, includeToJson: false)
+  $LoginRequestCopyWith<LoginRequest> get copyWith =>
+      throw _privateConstructorUsedError;
+}
+
+/// @nodoc
+abstract class $LoginRequestCopyWith<$Res> {
+  factory $LoginRequestCopyWith(
+          LoginRequest value, $Res Function(LoginRequest) then) =
+      _$LoginRequestCopyWithImpl<$Res, LoginRequest>;
+  @useResult
+  $Res call({String email, String password});
+}
+
+/// @nodoc
+class _$LoginRequestCopyWithImpl<$Res, $Val extends LoginRequest>
+    implements $LoginRequestCopyWith<$Res> {
+  _$LoginRequestCopyWithImpl(this._value, this._then);
+
+  // ignore: unused_field
+  final $Val _value;
+  // ignore: unused_field
+  final $Res Function($Val) _then;
+
+  /// Create a copy of LoginRequest
+  /// with the given fields replaced by the non-null parameter values.
+  @pragma('vm:prefer-inline')
+  @override
+  $Res call({
+    Object? email = null,
+    Object? password = null,
+  }) {
+    return _then(_value.copyWith(
+      email: null == email
+          ? _value.email
+          : email // ignore: cast_nullable_to_non_nullable
+              as String,
+      password: null == password
+          ? _value.password
+          : password // ignore: cast_nullable_to_non_nullable
+              as String,
+    ) as $Val);
+  }
+}
+
+/// @nodoc
+abstract class _$$LoginRequestImplCopyWith<$Res>
+    implements $LoginRequestCopyWith<$Res> {
+  factory _$$LoginRequestImplCopyWith(
+          _$LoginRequestImpl value, $Res Function(_$LoginRequestImpl) then) =
+      __$$LoginRequestImplCopyWithImpl<$Res>;
+  @override
+  @useResult
+  $Res call({String email, String password});
+}
+
+/// @nodoc
+class __$$LoginRequestImplCopyWithImpl<$Res>
+    extends _$LoginRequestCopyWithImpl<$Res, _$LoginRequestImpl>
+    implements _$$LoginRequestImplCopyWith<$Res> {
+  __$$LoginRequestImplCopyWithImpl(
+      _$LoginRequestImpl _value, $Res Function(_$LoginRequestImpl) _then)
+      : super(_value, _then);
+
+  /// Create a copy of LoginRequest
+  /// with the given fields replaced by the non-null parameter values.
+  @pragma('vm:prefer-inline')
+  @override
+  $Res call({
+    Object? email = null,
+    Object? password = null,
+  }) {
+    return _then(_$LoginRequestImpl(
+      email: null == email
+          ? _value.email
+          : email // ignore: cast_nullable_to_non_nullable
+              as String,
+      password: null == password
+          ? _value.password
+          : password // ignore: cast_nullable_to_non_nullable
+              as String,
+    ));
+  }
+}
+
+/// @nodoc
+@JsonSerializable()
+class _$LoginRequestImpl implements _LoginRequest {
+  const _$LoginRequestImpl({required this.email, required this.password});
+
+  factory _$LoginRequestImpl.fromJson(Map<String, dynamic> json) =>
+      _$$LoginRequestImplFromJson(json);
+
+  @override
+  final String email;
+  @override
+  final String password;
+
+  @override
+  String toString() {
+    return 'LoginRequest(email: $email, password: $password)';
+  }
+
+  @override
+  bool operator ==(Object other) {
+    return identical(this, other) ||
+        (other.runtimeType == runtimeType &&
+            other is _$LoginRequestImpl &&
+            (identical(other.email, email) || other.email == email) &&
+            (identical(other.password, password) ||
+                other.password == password));
+  }
+
+  @JsonKey(includeFromJson: false, includeToJson: false)
+  @override
+  int get hashCode => Object.hash(runtimeType, email, password);
+
+  /// Create a copy of LoginRequest
+  /// with the given fields replaced by the non-null parameter values.
+  @JsonKey(includeFromJson: false, includeToJson: false)
+  @override
+  @pragma('vm:prefer-inline')
+  _$$LoginRequestImplCopyWith<_$LoginRequestImpl> get copyWith =>
+      __$$LoginRequestImplCopyWithImpl<_$LoginRequestImpl>(this, _$identity);
+
+  @override
+  Map<String, dynamic> toJson() {
+    return _$$LoginRequestImplToJson(
+      this,
+    );
+  }
+}
+
+abstract class _LoginRequest implements LoginRequest {
+  const factory _LoginRequest(
+      {required final String email,
+      required final String password}) = _$LoginRequestImpl;
+
+  factory _LoginRequest.fromJson(Map<String, dynamic> json) =
+      _$LoginRequestImpl.fromJson;
+
+  @override
+  String get email;
+  @override
+  String get password;
+
+  /// Create a copy of LoginRequest
+  /// with the given fields replaced by the non-null parameter values.
+  @override
+  @JsonKey(includeFromJson: false, includeToJson: false)
+  _$$LoginRequestImplCopyWith<_$LoginRequestImpl> get copyWith =>
+      throw _privateConstructorUsedError;
+}