Refactor signup page to use BLoC pattern and implement authentication repository

- Updated signup.dart to replace Provider with BLoC for state management.
- Created AuthRepository to handle authentication logic and Firestore user management.
- Added TripRepository and UserRepository for trip and user data management.
- Implemented methods for user sign-in, sign-up, and data retrieval in repositories.
- Enhanced trip management with create, update, delete, and participant management functionalities.
- Updated AuthService to include new methods for sign-in and sign-up.
- Removed unnecessary print statements from TripService for cleaner code.
- Added dependencies for flutter_bloc and equatable in pubspec.yaml.

Not tested yet

lib/models/user.dart

@@ -1,79 +0,0 @@
-import 'dart:convert';
-
-class User {
-  final String? id;
-  final String nom;
-  final String prenom;
-  final String email;
-
-  User({
-    this.id,
-    required this.nom,
-    required this.prenom,
-    required this.email,
-  });
-
-  // Constructeur pour créer un User depuis un Map (utile pour Firebase)
-  factory User.fromMap(Map<String, dynamic> map) {
-    return User(
-      id: map['id'],
-      nom: map['nom'] ?? '',
-      prenom: map['prenom'] ?? '',
-      email: map['email'] ?? '',
-    );
-  }
-
-  // Constructeur pour créer un User depuis JSON
-  factory User.fromJson(String jsonStr) {
-    Map<String, dynamic> map = json.decode(jsonStr);
-    return User.fromMap(map);
-  }
-
-  // Méthode pour convertir un User en Map (utile pour Firebase)
-  Map<String, dynamic> toMap() {
-    return {
-      'id': id,
-      'nom': nom,
-      'prenom': prenom,
-      'email': email,
-    };
-  }
-
-  // Méthode pour convertir un User en JSON
-  String toJson() {
-    return json.encode(toMap());
-  }
-
-  // Méthode pour obtenir le nom complet
-  String get fullName => '$prenom $nom';
-
-  // Méthode pour créer une copie avec des modifications
-  User copyWith({
-    String? id,
-    String? nom,
-    String? prenom,
-    String? email,
-  }) {
-    return User(
-      id: id ?? this.id,
-      nom: nom ?? this.nom,
-      prenom: prenom ?? this.prenom,
-      email: email ?? this.email,
-    );
-  }
-
-  @override
-  String toString() {
-    return 'User(id: $id, nom: $nom, prenom: $prenom, email: $email)';
-  }
-
-  @override
-  bool operator ==(Object other) {
-    if (identical(this, other)) return true;
-    return other is User && other.email == email;
-  }
-
-  @override
-  int get hashCode => email.hashCode;
-}
-