feat(mobile): consolidation modules epargne, messaging, organisations

- Epargne: badge LCB-FT (bouclier ambre) sur comptes avec fonds bloques + note recap
- EpargneDetail: historique pagine (page/size), affichage soldeAvant/soldeApres/motif dans chaque transaction, bouton "Charger plus"
- TransactionEpargneRepository: getByCompte accepte page et size, gere reponse paginee Spring (content[])
- MessagingDatasource: markMessageAsRead silencieuse (pas d'endpoint unitaire), getUnreadCount somme unreadCount des conversations
- OrganizationDetail: _memberCount charge le vrai nombre depuis GET /membres/count, affiche la valeur reelle au lieu de nombreMembres (toujours 0)

lib/features/organizations/presentation/pages/organization_detail_page.dart

@@ -3,11 +3,13 @@ library organisation_detail_page;
 
 import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
+import 'package:get_it/get_it.dart';
 import 'package:url_launcher/url_launcher.dart';
 import '../../data/models/organization_model.dart';
 import '../../bloc/organizations_bloc.dart';
 import '../../bloc/organizations_event.dart';
 import '../../bloc/organizations_state.dart';
+import '../../domain/repositories/organization_repository.dart';
 import 'edit_organization_page.dart';
 import '../../../../shared/design_system/tokens/app_colors.dart';
 import '../../../../features/authentication/presentation/bloc/auth_bloc.dart';
@@ -23,10 +25,20 @@ class OrganizationDetailPage extends StatefulWidget {
 }
 
 class _OrganizationDetailPageState extends State<OrganizationDetailPage> {
+  int? _memberCount;
+
   @override
   void initState() {
     super.initState();
     context.read<OrganizationsBloc>().add(LoadOrganizationById(widget.organizationId));
+    _loadMemberCount();
+  }
+
+  Future<void> _loadMemberCount() async {
+    try {
+      final count = await GetIt.I<IOrganizationRepository>().getMembreCount(widget.organizationId);
+      if (mounted) setState(() => _memberCount = count);
+    } catch (_) {}
   }
 
   @override
@@ -214,7 +226,7 @@ class _OrganizationDetailPageState extends State<OrganizationDetailPage> {
   Widget _buildStatsCard(OrganizationModel org) {
     return _buildCard('Statistiques', Icons.bar_chart, [
       Row(children: [
-        Expanded(child: _buildStatItem(Icons.people, 'Membres', org.nombreMembres.toString(), AppColors.primaryGreen)),
+        Expanded(child: _buildStatItem(Icons.people, 'Membres', (_memberCount ?? org.nombreMembres).toString(), AppColors.primaryGreen)),
         const SizedBox(width: 10),
         Expanded(child: _buildStatItem(Icons.admin_panel_settings, 'Admins', org.nombreAdministrateurs.toString(), AppColors.brandGreen)),
         const SizedBox(width: 10),