fix: честные ошибки при вводе пароля и дубликат в Keychain

lib/backend/modules/account/account_models.dart

@@ -290,6 +290,12 @@ class WrongDeviceTokenException implements Exception {
   String toString() => 'WrongDeviceTokenException';
 }
 
+class WrongPasswordException implements Exception {
+  const WrongPasswordException();
+  @override
+  String toString() => 'WrongPasswordException';
+}
+
 class RequestCodeResult {
   final String token;
 

lib/backend/modules/account/two_factor_module.dart

@@ -124,7 +124,7 @@ class TwoFactorModule extends AccountApiBase {
     checkPacketError(packet, 'check2faPassword');
     final data = packet.payload;
     if (data is Map && data['error'] != null) {
-      throw Exception('Неверный пароль');
+      throw const WrongPasswordException();
     }
   }