Show error message longer (10s) when email generation fails

lib/features/emails/presentation/email_compose_screen.dart

@@ -67,7 +67,14 @@ class _EmailComposeScreenState extends ConsumerState<EmailComposeScreen> {
     } catch (e) {
       if (mounted) {
         ScaffoldMessenger.of(context).showSnackBar(
-          SnackBar(content: Text('Failed to generate: $e')),
+          SnackBar(
+            content: Text('Failed to generate: $e'),
+            duration: const Duration(seconds: 10),
+            action: SnackBarAction(
+              label: 'Dismiss',
+              onPressed: () {},
+            ),
+          ),
         );
       }
     } finally {