feat(01-02): create AuthUser data model

- AuthUser class wraps Supabase User for clean architecture
- Includes fromSupabase() factory constructor for conversion
- Provides copyWith() method for immutable updates
- Contains essential fields: id, email, created_at, email_verified
- Optional fields: display_name, avatar_url, last_sign_in_at
- Proper null safety and equality operators implemented

lib/features/authentication/data/models/auth_user.dart

@@ -0,0 +1,110 @@
+import 'package:supabase_flutter/supabase_flutter.dart';
+
+/// AuthUser data model representing a user in the authentication system.
+/// 
+/// This model provides a clean abstraction over Supabase's User model,
+/// following clean architecture principles for the data layer.
+class AuthUser {
+  /// Unique identifier for the user
+  final String id;
+  
+  /// User's email address
+  final String email;
+  
+  /// Timestamp when the user account was created
+  final DateTime createdAt;
+  
+  /// Whether the user's email has been verified
+  final bool emailVerified;
+  
+  /// User's display name (optional)
+  final String? displayName;
+  
+  /// User's avatar URL (optional)
+  final String? avatarUrl;
+  
+  /// Timestamp when the user was last seen
+  final DateTime? lastSignInAt;
+  
+  /// Creates a new AuthUser instance
+  const AuthUser({
+    required this.id,
+    required this.email,
+    required this.createdAt,
+    required this.emailVerified,
+    this.displayName,
+    this.avatarUrl,
+    this.lastSignInAt,
+  });
+  
+  /// Creates an AuthUser from a Supabase User object
+  /// 
+  /// [user] - The Supabase User object to convert
+  /// Returns an AuthUser with mapped fields
+  factory AuthUser.fromSupabase(User user) {
+    return AuthUser(
+      id: user.id,
+      email: user.email ?? '',
+      createdAt: user.createdAt ?? DateTime.now(),
+      emailVerified: user.emailConfirmedAt != null,
+      displayName: user.userMetadata?['display_name'] as String?,
+      avatarUrl: user.userMetadata?['avatar_url'] as String?,
+      lastSignInAt: user.lastSignInAt,
+    );
+  }
+  
+  /// Creates a copy of this AuthUser with updated values
+  /// 
+  /// Allows for immutable updates to user data
+  AuthUser copyWith({
+    String? id,
+    String? email,
+    DateTime? createdAt,
+    bool? emailVerified,
+    String? displayName,
+    String? avatarUrl,
+    DateTime? lastSignInAt,
+  }) {
+    return AuthUser(
+      id: id ?? this.id,
+      email: email ?? this.email,
+      createdAt: createdAt ?? this.createdAt,
+      emailVerified: emailVerified ?? this.emailVerified,
+      displayName: displayName ?? this.displayName,
+      avatarUrl: avatarUrl ?? this.avatarUrl,
+      lastSignInAt: lastSignInAt ?? this.lastSignInAt,
+    );
+  }
+  
+  /// Returns a string representation of the user for debugging
+  @override
+  String toString() {
+    return 'AuthUser(id: $id, email: $email, emailVerified: $emailVerified, displayName: $displayName)';
+  }
+  
+  /// Returns true if the user is considered authenticated
+  /// 
+  /// A user is authenticated if they have a valid ID and email
+  bool get isAuthenticated => id.isNotEmpty && email.isNotEmpty;
+  
+  /// Returns true if the user's email is verified
+  bool get isEmailVerified => emailVerified;
+  
+  /// Equality operator for comparing AuthUser objects
+  @override
+  bool operator ==(Object other) {
+    if (identical(this, other)) return true;
+    return other is AuthUser &&
+        other.id == id &&
+        other.email == email &&
+        other.emailVerified == emailVerified;
+  }
+  
+  /// Hash code for AuthUser objects
+  @override
+  int get hashCode {
+    return id.hashCode ^
+        email.hashCode ^
+        emailVerified.hashCode;
+  }
+}