feat(frontend): improve application feedback messages

eme-frontend/lib/screens/home_screen.dart

@@ -3,6 +3,7 @@ import "package:google_fonts/google_fonts.dart";
 import "../demo_identity.dart";
 import "../services/auth_service.dart";
 import "../theme/ensup_colors.dart";
+import "../widgets/app_message.dart";
 import "../widgets/ensup_top_bar.dart";
 import "../widgets/profile_card.dart";
 import "../widgets/action_card.dart";
@@ -22,9 +23,7 @@ class HomeScreen extends StatelessWidget {
       }
     } catch (error) {
       if (!context.mounted) return;
-      ScaffoldMessenger.of(
-        context,
-      ).showSnackBar(SnackBar(content: Text(error.toString())));
+      AppMessage.erreur(context, error);
     }
   }