feat(frontend): simulate authenticated user sessions

eme-frontend/lib/screens/responsable_screen.dart

@@ -2,6 +2,7 @@ import "package:flutter/material.dart";
 import "package:google_fonts/google_fonts.dart";
 
 import "../demo_identity.dart";
+import "../services/auth_service.dart";
 import "../services/responsable_service.dart";
 import "../theme/ensup_colors.dart";
 import "../utils/file_download.dart";
@@ -44,6 +45,11 @@ class _ResponsableScreenState extends State<ResponsableScreen> {
     setState(() => _future = _charger());
   }
 
+  void _quitter() {
+    AuthService.clearSession();
+    Navigator.of(context).pop();
+  }
+
   Future<void> _changerStatut(Map<String, dynamic> anomalie) async {
     final prochain = _prochainStatut(anomalie["statut"] as String?);
     if (prochain == null || _transitionEnCours) {
@@ -124,10 +130,7 @@ class _ResponsableScreenState extends State<ResponsableScreen> {
       body: SafeArea(
         child: Column(
           children: [
-            _ResponsableTopBar(
-              onExit: () => Navigator.of(context).pop(),
-              onRefresh: _rafraichir,
-            ),
+            _ResponsableTopBar(onExit: _quitter, onRefresh: _rafraichir),
             Expanded(
               child: FutureBuilder<_ResponsableData>(
                 future: _future,
@@ -249,7 +252,7 @@ class _ResponsableScreenState extends State<ResponsableScreen> {
                 anomaliesActives: anomaliesActives,
                 notificationsNonLues: notificationsNonLues,
                 onChanged: (index) => setState(() => _onglet = index),
-                onExit: () => Navigator.of(context).pop(),
+                onExit: _quitter,
               ),
             Expanded(
               child: Column(