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/message/message_state.dart

@@ -1,6 +1,27 @@
+/// States for message-related operations in the MessageBloc.
+///
+/// This file defines all possible states that the MessageBloc can emit in response
+/// to message-related events. The states represent different phases of message
+/// operations including loading, success, and error states for real-time chat functionality.
+///
+/// State Categories:
+/// - **Initial State**: MessageInitial
+/// - **Loading States**: MessageLoading
+/// - **Success States**: MessagesLoaded
+/// - **Error States**: MessageError
+///
+/// The states support real-time chat features including message streaming,
+/// reactions, editing, and deletion within group conversations.
+///
+/// All states extend [MessageState] and implement [Equatable] for proper
+/// equality comparison and state change detection in the BLoC pattern.
 import 'package:equatable/equatable.dart';
 import '../../models/message.dart';
 
+/// Base class for all message-related states.
+///
+/// All message states must extend this class and implement the [props] getter
+/// for proper equality comparison in the BLoC pattern.
 abstract class MessageState extends Equatable {
   const MessageState();
 
@@ -8,14 +29,41 @@ abstract class MessageState extends Equatable {
   List<Object?> get props => [];
 }
 
+/// The initial state of the MessageBloc before any operations are performed.
+///
+/// This is the default state when the bloc is first created and represents
+/// a clean slate with no message data loaded or operations in progress.
 class MessageInitial extends MessageState {}
 
+/// State indicating that a message operation is currently in progress.
+///
+/// This state is emitted when the bloc is performing operations like
+/// loading messages or initializing the real-time message stream.
+/// UI components can use this state to show loading indicators.
 class MessageLoading extends MessageState {}
 
+/// State containing a list of successfully loaded messages for a group.
+///
+/// This state is emitted when messages have been successfully retrieved
+/// from the repository, either through initial loading or real-time updates.
+/// The state includes both the messages and the group ID for context.
+/// The UI can use this data to display the chat conversation.
+///
+/// Properties:
+///   [messages]: List of Message objects in the conversation
+///   [groupId]: The unique identifier of the group these messages belong to
 class MessagesLoaded extends MessageState {
+  /// The list of messages in the conversation
   final List<Message> messages;
+  
+  /// The unique identifier of the group
   final String groupId;
 
+  /// Creates a MessagesLoaded state.
+  ///
+  /// Args:
+  ///   [messages]: The list of messages to include in this state
+  ///   [groupId]: The group ID these messages belong to
   const MessagesLoaded({
     required this.messages,
     required this.groupId,
@@ -25,9 +73,23 @@ class MessagesLoaded extends MessageState {
   List<Object?> get props => [messages, groupId];
 }
 
+/// State indicating that a message operation has failed.
+///
+/// This state is emitted when any message operation encounters an error,
+/// such as failing to load messages, send a message, or perform other
+/// message-related operations. It contains an error message that can be
+/// displayed to the user to explain what went wrong.
+///
+/// Properties:
+///   [message]: An error message describing what went wrong
 class MessageError extends MessageState {
+  /// The error message to display to the user
   final String message;
 
+  /// Creates a MessageError state.
+  ///
+  /// Args:
+  ///   [message]: The error message to display
   const MessageError(this.message);
 
   @override