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_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;