Fix biometric enable - reset auth state first to force prompt

lib/services/auth_service.dart

@@ -157,7 +157,10 @@ class AuthService extends ChangeNotifier {
   
   /// Enable biometric authentication for future logins
   Future<bool> enableBiometric() async {
-    // First verify user can authenticate
+    // Reset auth state so we actually prompt the user
+    _biometricService.resetAuthState();
+    
+    // Now verify user can authenticate
     final result = await _biometricService.authenticate(
       reason: 'Verify your identity to enable biometric login',
     );