feat(features): refontes adhesions/admin/auth/backup/contributions/dashboard/epargne/events

- adhesions : bloc complet avec events/states/model, dialogs paiement/rejet
- admin : users bloc, user management list/detail pages
- authentication : bloc + keycloak auth service + webview
- backup : bloc complet, repository, models
- contributions : bloc + widgets + export
- dashboard : widgets connectés (activities, events, notifications, search)
  + charts + monitoring + shortcuts
- epargne : repository, transactions, dialogs
- events : bloc complet, pages (detail, connected, wrapper), models

lib/features/epargne/presentation/widgets/depot_epargne_dialog.dart

@@ -7,6 +7,7 @@ import 'package:file_picker/file_picker.dart';
 import '../../../../core/constants/lcb_ft_constants.dart';
 import '../../../../core/data/repositories/parametres_lcb_ft_repository.dart';
 import '../../../../core/utils/error_formatter.dart';
+import '../../../../shared/design_system/tokens/app_colors.dart';
 import '../../data/models/transaction_epargne_request.dart';
 import '../../data/repositories/transaction_epargne_repository.dart';
 import '../../data/services/document_upload_service.dart';
@@ -116,7 +117,7 @@ class _DepotEpargneDialogState extends State<DepotEpargneDialog> {
       ScaffoldMessenger.of(context).showSnackBar(
         const SnackBar(
           content: Text('✓ Pièce justificative uploadée avec succès'),
-          backgroundColor: Colors.green,
+          backgroundColor: AppColors.success,
         ),
       );
     } catch (e) {
@@ -128,7 +129,7 @@ class _DepotEpargneDialogState extends State<DepotEpargneDialog> {
       ScaffoldMessenger.of(context).showSnackBar(
         SnackBar(
           content: Text('Erreur upload : ${e.toString()}'),
-          backgroundColor: Colors.red,
+          backgroundColor: AppColors.error,
         ),
       );
     }
@@ -334,7 +335,7 @@ class _DepotEpargneDialogState extends State<DepotEpargneDialog> {
                           )
                         : Icon(
                             _pieceJustificativeId != null ? Icons.check_circle : Icons.attach_file,
-                            color: _pieceJustificativeId != null ? Colors.green : null,
+                            color: _pieceJustificativeId != null ? AppColors.success : null,
                           ),
                     label: Text(
                       _pieceJustificativeId != null
@@ -344,7 +345,7 @@ class _DepotEpargneDialogState extends State<DepotEpargneDialog> {
                     style: OutlinedButton.styleFrom(
                       minimumSize: const Size(double.infinity, 48),
                       side: _pieceJustificativeId != null
-                          ? const BorderSide(color: Colors.green)
+                          ? const BorderSide(color: AppColors.success)
                           : null,
                     ),
                   ),
@@ -362,7 +363,7 @@ class _DepotEpargneDialogState extends State<DepotEpargneDialog> {
                     child: Text(
                       'Photo ou PDF (max 5 MB)',
                       style: Theme.of(context).textTheme.bodySmall?.copyWith(
-                            color: Colors.grey,
+                            color: AppColors.textTertiary,
                           ),
                     ),
                   ),