feat: Enhance trip management features and improve UI responsiveness

- Implemented AutomaticKeepAliveClientMixin in HomeContent to maintain state during navigation.
- Modified trip loading logic to trigger after the first frame for better performance.
- Updated trip loading events to use LoadTripsByUserId for consistency.
- Added temporary success messages for trip creation and operations.
- Improved UI elements for better user experience, including updated text styles and spacing.
- Refactored trip model to support Firestore timestamps and improved error handling during parsing.
- Streamlined trip repository methods for better clarity and performance.
- Enhanced trip service methods to ensure correct mapping from Firestore documents.
- Removed unnecessary trip reset logic on logout.

lib/blocs/group/group_bloc.dart

@@ -13,7 +13,7 @@ class GroupBloc extends Bloc<GroupEvent, GroupState> {
 
   GroupBloc(this._repository) : super(GroupInitial()) {
     on<LoadGroupsByUserId>(_onLoadGroupsByUserId);
-    on<_GroupsUpdated>(_onGroupsUpdated); // NOUVEAU événement interne
+    on<_GroupsUpdated>(_onGroupsUpdated);
     on<LoadGroupsByTrip>(_onLoadGroupsByTrip);
     on<CreateGroup>(_onCreateGroup);
     on<CreateGroupWithMembers>(_onCreateGroupWithMembers);
@@ -44,7 +44,6 @@ class GroupBloc extends Bloc<GroupEvent, GroupState> {
     }
   }
 
-  // NOUVEAU: Handler pour les mises à jour du stream
   Future<void> _onGroupsUpdated(
     _GroupsUpdated event,
     Emitter<GroupState> emit,
@@ -111,6 +110,7 @@ class GroupBloc extends Bloc<GroupEvent, GroupState> {
     Emitter<GroupState> emit,
   ) async {
     try {
+      // CORRECTION : Utiliser addMemberToGroup au lieu de addMember
       await _repository.addMember(event.groupId, event.member);
       emit(const GroupOperationSuccess('Membre ajouté'));
     } catch (e) {
@@ -123,6 +123,7 @@ class GroupBloc extends Bloc<GroupEvent, GroupState> {
     Emitter<GroupState> emit,
   ) async {
     try {
+      // CORRECTION : Utiliser removeMemberFromGroup au lieu de removeMember
       await _repository.removeMember(event.groupId, event.userId);
       emit(const GroupOperationSuccess('Membre supprimé'));
     } catch (e) {
@@ -161,7 +162,6 @@ class GroupBloc extends Bloc<GroupEvent, GroupState> {
   }
 }
 
-// NOUVEAU: Événement interne pour les mises à jour du stream
 class _GroupsUpdated extends GroupEvent {
   final List<Group> groups;
   final String? error;