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/account/account_bloc.dart

@@ -1,3 +1,26 @@
+/// A BLoC (Business Logic Component) that manages account-related state and operations.
+///
+/// This bloc handles account operations such as loading accounts by user ID,
+/// creating new accounts, and managing real-time updates from the account repository.
+/// It uses stream subscriptions to listen for account changes and emits corresponding states.
+///
+/// The bloc supports the following operations:
+/// - Loading accounts by user ID with real-time updates
+/// - Creating a single account without members
+/// - Creating an account with associated members
+///
+/// All errors are logged using [ErrorService] and emitted as [AccountError] states.
+///
+/// Example usage:
+/// ```dart
+/// final accountBloc = AccountBloc(accountRepository);
+/// accountBloc.add(LoadAccountsByUserId('user123'));
+/// ```
+///
+/// Remember to close the bloc when done to cancel active subscriptions:
+/// ```dart
+/// accountBloc.close();
+/// ```
 import 'dart:async';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:travel_mate/services/error_service.dart';

lib/blocs/account/account_event.dart

@@ -1,14 +1,23 @@
 import 'package:equatable/equatable.dart';
-import '../../models/account.dart';
-import '../../models/group_member.dart';
+import 'package:travel_mate/models/account.dart';
+import 'package:travel_mate/models/group_member.dart';
 
+
+/// Abstract base class for account-related events in the BLoC pattern.
+/// 
+/// This class extends [Equatable] to enable value comparison for events.
+/// All account events should inherit from this class and implement the [props] getter.
 abstract class AccountEvent extends Equatable {
   const AccountEvent();
 
   @override
   List<Object?> get props => [];
-} 
+}
 
+/// Event to load accounts associated with a specific user ID.
+/// 
+/// This event is dispatched when the application needs to fetch accounts
+/// for a given user, typically for displaying user-specific account data.
 class LoadAccountsByUserId extends AccountEvent {
   final String userId;
 
@@ -18,6 +27,10 @@ class LoadAccountsByUserId extends AccountEvent {
   List<Object?> get props => [userId];
 }
 
+/// Event to load accounts associated with a specific trip.
+/// 
+/// This event is dispatched when the application needs to fetch accounts
+/// related to a particular trip, such as for trip expense management.
 class LoadAccountsByTrip extends AccountEvent {
   final String tripId;
 
@@ -27,6 +40,10 @@ class LoadAccountsByTrip extends AccountEvent {
   List<Object?> get props => [tripId];
 }
 
+/// Event to create a new account.
+/// 
+/// This event is dispatched when a new account needs to be created,
+/// passing the [Account] object containing the account details.
 class CreateAccount extends AccountEvent {
   final Account account;
 
@@ -36,6 +53,10 @@ class CreateAccount extends AccountEvent {
   List<Object?> get props => [account];
 }
 
+/// Event to update an existing account.
+/// 
+/// This event is dispatched when an account needs to be modified,
+/// requiring the [accountId] to identify the account and the updated [Account] object.
 class UpdateAccount extends AccountEvent {
   final String accountId;
   final Account account;
@@ -49,6 +70,10 @@ class UpdateAccount extends AccountEvent {
   List<Object?> get props => [accountId, account];
 }
 
+/// Event to create a new account along with its group members.
+/// 
+/// This event is dispatched when creating an account that includes
+/// a list of [GroupMember] objects, such as for shared trip accounts.
 class CreateAccountWithMembers extends AccountEvent {
   final Account account;
   final List<GroupMember> members;

lib/blocs/account/account_state.dart

@@ -1,3 +1,38 @@
+/// The abstract base class for all account-related states used by the AccountBloc.
+///
+/// Extends Equatable to enable value-based comparisons between state
+/// instances. Subclasses should provide the relevant properties by
+/// overriding `props` so that the bloc can correctly determine whether
+/// the state has changed.
+ 
+/// Represents the initial state of the account feature.
+///
+/// Used before any account-related action has started or when the bloc
+/// has been freshly created.
+ 
+/// Indicates that an account-related operation is currently in progress.
+///
+/// This state is typically emitted while fetching account data, creating,
+/// updating, or deleting an account so the UI can show a loading indicator.
+ 
+/// Emitted when a collection of accounts has been successfully loaded.
+///
+/// Contains:
+/// - `accounts`: the list of Account models retrieved from the repository.
+///
+/// Use this state to display fetched account data in the UI.
+ 
+/// Represents a successful account operation that does not necessarily
+/// carry account data (e.g., after creating, updating, or deleting an account).
+///
+/// Contains:
+/// - `message`: a human-readable success message that can be shown to the user.
+ 
+/// Represents an error that occurred during an account-related operation.
+///
+/// Contains:
+/// - `message`: a human-readable error description suitable for logging
+///   or displaying to the user.
 import 'package:equatable/equatable.dart';
 import '../../models/account.dart';