[#1] Feat: 유저 모델 추가

lib/models/user.dart

@@ -0,0 +1,30 @@
+class User {
+  final String? name;
+  final String? email;
+  List<String>? followingList;
+
+  User({required this.name, required this.email, this.followingList});
+
+  Map<String, dynamic> toJson() {
+    return {
+      'userName': name,
+      'email': email,
+    };
+  }
+
+  factory User.fromJson(Map<String, dynamic> json) {
+    return User(
+      name: json['userName'] as String?,
+      email: json['email'] as String?,
+      followingList: json['followingList'] != null ? List<String>.from(json['followingList']) : null
+    );
+  }
+
+  User copyWith({String? name, String? email, List<String>? followingList}) {
+    return User(
+      name: name ?? this.name,
+      email: email ?? this.email,
+      followingList: followingList ?? this.followingList
+    );
+  }
+}