Added core data models, repositories, and utilities

lifetimer/lib/data/models/user_model.dart

@@ -76,4 +76,38 @@ class User extends Equatable {
         createdAt,
         updatedAt,
       ];
+
+  Map<String, dynamic> toJson() {
+    return {
+      'id': id,
+      'username': username,
+      'email': email,
+      'avatar_url': avatarUrl,
+      'bio': bio,
+      'is_public_profile': isPublicProfile,
+      'countdown_start_date': countdownStartDate?.toIso8601String(),
+      'countdown_end_date': countdownEndDate?.toIso8601String(),
+      'created_at': createdAt.toIso8601String(),
+      'updated_at': updatedAt.toIso8601String(),
+    };
+  }
+
+  factory User.fromJson(Map<String, dynamic> json) {
+    return User(
+      id: json['id'] as String,
+      username: json['username'] as String,
+      email: json['email'] as String,
+      avatarUrl: json['avatar_url'] as String?,
+      bio: json['bio'] as String?,
+      isPublicProfile: json['is_public_profile'] as bool? ?? false,
+      countdownStartDate: json['countdown_start_date'] != null
+          ? DateTime.parse(json['countdown_start_date'] as String)
+          : null,
+      countdownEndDate: json['countdown_end_date'] != null
+          ? DateTime.parse(json['countdown_end_date'] as String)
+          : null,
+      createdAt: DateTime.parse(json['created_at'] as String),
+      updatedAt: DateTime.parse(json['updated_at'] as String),
+    );
+  }
 }