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';