Enhance model and service documentation with detailed comments and descriptions

- Updated Group, Trip, User, and other model classes to include comprehensive documentation for better understanding and maintainability.
- Improved error handling and logging in services, including AuthService, ErrorService, and StorageService.
- Added validation and business logic explanations in ExpenseService and TripService.
- Refactored method comments to follow a consistent format across the codebase.
- Translated error messages and comments from French to English for consistency.

lib/blocs/trip/trip_state.dart

@@ -1,6 +1,27 @@
+/// States for trip-related operations in the TripBloc.
+///
+/// This file defines all possible states that the TripBloc can emit in response
+/// to trip-related events. The states represent different phases of trip
+/// operations including loading, success, error, and data states for trip management.
+///
+/// State Categories:
+/// - **Initial State**: TripInitial
+/// - **Loading States**: TripLoading
+/// - **Success States**: TripLoaded, TripCreated, TripOperationSuccess
+/// - **Error States**: TripError
+///
+/// The states support complete trip lifecycle management with proper feedback
+/// for create, read, update, and delete operations.
+///
+/// All states extend [TripState] and implement [Equatable] for proper
+/// equality comparison and state change detection in the BLoC pattern.
 import 'package:equatable/equatable.dart';
 import '../../models/trip.dart';
 
+/// Base class for all trip-related states.
+///
+/// All trip states must extend this class and implement the [props] getter
+/// for proper equality comparison in the BLoC pattern.
 abstract class TripState extends Equatable {
   const TripState();
 
@@ -8,44 +29,111 @@ abstract class TripState extends Equatable {
   List<Object?> get props => [];
 }
 
+/// The initial state of the TripBloc before any operations are performed.
+///
+/// This is the default state when the bloc is first created and represents
+/// a clean slate with no trip data loaded or operations in progress.
 class TripInitial extends TripState {}
 
+/// State indicating that a trip operation is currently in progress.
+///
+/// This state is emitted when the bloc is performing operations like
+/// loading trips, creating trips, updating trip information, or deleting trips.
+/// UI components can use this state to show loading indicators.
 class TripLoading extends TripState {}
 
+/// State containing a list of successfully loaded trips.
+///
+/// This state is emitted when trips have been successfully retrieved
+/// from the repository, either through initial loading or real-time updates.
+/// The UI can use this data to display the list of available trips for the user.
+///
+/// Properties:
+///   [trips]: List of Trip objects that were loaded
 class TripLoaded extends TripState {
+  /// The list of loaded trips
   final List<Trip> trips;
 
+  /// Creates a TripLoaded state.
+  ///
+  /// Args:
+  ///   [trips]: The list of trips to include in this state
   const TripLoaded(this.trips);
 
   @override
   List<Object?> get props => [trips];
 }
 
+/// State indicating successful trip creation.
+///
+/// This state is emitted when a new trip has been successfully created.
+/// It contains the ID of the newly created trip and a success message
+/// that can be displayed to the user. This state is typically followed
+/// by automatic reloading of the user's trip list.
+///
+/// Properties:
+///   [tripId]: The unique identifier of the newly created trip
+///   [message]: A success message to display to the user
 class TripCreated extends TripState {
+  /// The unique identifier of the newly created trip
   final String tripId;
+  
+  /// Success message for the user
   final String message;
 
+  /// Creates a TripCreated state.
+  ///
+  /// Args:
+  ///   [tripId]: The ID of the newly created trip
+  ///   [message]: Optional success message (defaults to "Trip created successfully")
   const TripCreated({
     required this.tripId,
-    this.message = 'Voyage créé avec succès',
+    this.message = 'Trip created successfully',
   });
 
   @override
   List<Object?> get props => [tripId, message];
 }
 
+/// State indicating successful completion of a trip operation.
+///
+/// This state is emitted when operations like updating or deleting trips
+/// have completed successfully. It contains a message that can be displayed
+/// to inform the user of the successful operation. This state is typically
+/// followed by automatic reloading of the user's trip list.
+///
+/// Properties:
+///   [message]: A success message describing the completed operation
 class TripOperationSuccess extends TripState {
+  /// The success message to display to the user
   final String message;
 
+  /// Creates a TripOperationSuccess state.
+  ///
+  /// Args:
+  ///   [message]: The success message to display
   const TripOperationSuccess(this.message);
 
   @override
   List<Object?> get props => [message];
 }
 
+/// State indicating that a trip operation has failed.
+///
+/// This state is emitted when any trip operation encounters an error.
+/// It contains an error message that can be displayed to the user to
+/// explain what went wrong during the operation.
+///
+/// Properties:
+///   [message]: An error message describing what went wrong
 class TripError extends TripState {
+  /// The error message to display to the user
   final String message;
 
+  /// Creates a TripError state.
+  ///
+  /// Args:
+  ///   [message]: The error message to display
   const TripError(this.message);
 
   @override