feat: Add logger service and improve expense dialog with enhanced receipt management and calculation logic.

lib/components/group/group_content.dart

@@ -144,12 +144,9 @@ class _GroupContentState extends State<GroupContent> {
       final color = colors[group.name.hashCode.abs() % colors.length];
 
       // Membres de manière simple
-      String memberInfo = '${group.members.length} membre(s)';
+      String memberInfo = '${group.memberIds.length} membre(s)';
       if (group.members.isNotEmpty) {
-        final names = group.members
-            .take(2)
-            .map((m) => m.firstName)
-            .join(', ');
+        final names = group.members.take(2).map((m) => m.firstName).join(', ');
         memberInfo += '\n$names';
       }