Settings fingerprint = flag only (no biometric prompt there); real prompt at login when enabled+registered. Msg color: green=on, grey=off

lib/settings_screen.dart

@@ -19,7 +19,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
   final _oldCtrl = TextEditingController();
   final _newCtrl = TextEditingController();
   String? _msg;
-  Color _msgColor = Colors.green;
+  Color _msgColor = Colors.grey;
   bool _biometricOn = false;
   bool _biometricAvailable = false;
   int _timeout = 3;
@@ -80,22 +80,17 @@ class _SettingsScreenState extends State<SettingsScreen> {
       });
       return;
     }
-    // optimistic: move switch immediately so it feels responsive
-    if (mounted) setState(() => _biometricOn = value);
-    if (value) {
-      final (ok, err) = await widget.auth.authenticateWithBiometrics();
-      if (!ok) {
-        if (mounted) {
-          setState(() {
-            _biometricOn = false;
-            _msg = 'Verifikasi biometrik gagal: ${err ?? "dibatalkan"}';
-            _msgColor = Colors.red;
-          });
-        }
-        return;
-      }
-    }
+    // Settings only sets the flag; actual biometric prompt happens at login.
     await widget.auth.setBiometricEnabled(value);
+    if (mounted) {
+      setState(() {
+        _biometricOn = value;
+        _msg = value
+            ? 'Sidik jari aktif. Akan diminta saat login.'
+            : 'Sidik jari nonaktif.';
+        _msgColor = value ? Colors.green : Colors.grey;
+      });
+    }
   }
 
   Future<void> _setTimeout(int? value) async {