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/components/home/create_trip_content.dart

@@ -20,8 +20,29 @@ import '../../repositories/group_repository.dart';
 import 'package:http/http.dart' as http;
 import 'package:flutter_dotenv/flutter_dotenv.dart';
 
+/// Create trip content widget for trip creation and editing functionality.
+/// 
+/// This widget provides a comprehensive form interface for creating new trips
+/// or editing existing ones. Key features include:
+/// - Trip creation with validation
+/// - Location search with autocomplete
+/// - Date selection for trip duration
+/// - Budget planning and management
+/// - Group creation and member management
+/// - Account setup for expense tracking
+/// - Integration with mapping services for location selection
+/// 
+/// The widget handles both creation and editing modes based on the
+/// provided tripToEdit parameter.
 class CreateTripContent extends StatefulWidget {
+  /// Optional trip to edit. If null, creates a new trip
   final Trip? tripToEdit;
+  
+  /// Creates a create trip content widget.
+  /// 
+  /// Args:
+  ///   [tripToEdit]: Optional trip to edit. If provided, the form will
+  ///                 be populated with existing trip data for editing
   const CreateTripContent({
     super.key,
     this.tripToEdit,
@@ -32,30 +53,44 @@ class CreateTripContent extends StatefulWidget {
 }
 
 class _CreateTripContentState extends State<CreateTripContent> {
+  /// Service for handling and displaying errors
   final _errorService = ErrorService();
+  
+  /// Form validation key
   final _formKey = GlobalKey<FormState>();
+  
+  /// Text controllers for form fields
   final _titleController = TextEditingController();
   final _descriptionController = TextEditingController();
   final _locationController = TextEditingController();
   final _budgetController = TextEditingController();
+  final _participantController = TextEditingController();
+  
+  /// Services for user and group operations
   final _userService = UserService();
   final _groupRepository = GroupRepository();
 
+  /// Trip date variables
   DateTime? _startDate;
   DateTime? _endDate;
+  
+  /// Loading and state management variables
   bool _isLoading = false;
   String? _createdTripId;
 
+  /// Google Maps API key for location services
   static final String _apiKey = dotenv.env['GOOGLE_MAPS_API_KEY'] ?? '';
 
+  /// Participant management
   final List<String> _participants = [];
-  final _participantController = TextEditingController();
 
+  /// Location autocomplete functionality
   List<PlaceSuggestion> _placeSuggestions = [];
   bool _isLoadingSuggestions = false;
   OverlayEntry? _suggestionsOverlay;
   final LayerLink _layerLink = LayerLink();
 
+  /// Determines if the widget is in editing mode
   bool get isEditing => widget.tripToEdit != null;
 
   @override