feat: confirm before leaving a game, and fix untranslated strings

Exit confirmation
- A dialog in the app's own style now guards every in-game screen. The safe
  action is the prominent one, so a stray tap keeps you in the game.
- Eleven screens covered, against both the system back gesture and the close
  buttons. The message adapts: a single-device game is lost, a host ends it
  for everyone, a client can rejoin.
- The two screens the host also opens from the manager take a flag so that
  back there just closes them instead of offering to quit.

Translations
- 21 keys were still holding the English text in Arabic, Basque, Hindi,
  Japanese, Korean, Dutch, Polish, Russian, Turkish and both Chinese
  variants: 231 strings, covering the whole multi-device flow, permissions
  and the mode picker. Nothing failed, the app just showed English.
- The permissions dialog was hardcoded in Spanish; it is localized now.
- Portuguese used Spanish gerunds where pt-PT takes "a + infinitive".

Checked what looked untranslated but is not: Animals and Notes are correct
Catalan, Configuration and Vibration correct French, Version correct German.
Those are whitelisted in the new test rather than silently rewritten.

l10n_cobertura_test guards all of it: no missing or orphan keys, no empty
values, no English left outside the whitelist, and placeholders preserved.

lib/l10n/generated/app_localizations_ko.dart

@@ -645,84 +645,77 @@ class AppLocalizationsKo extends AppLocalizations {
   String get delete => '삭제';
 
   @override
-  String get selectAtLeastThreeUsersToStart =>
-      'Select at least 3 users to start.';
+  String get selectAtLeastThreeUsersToStart => '시작하려면 사용자를 3명 이상 선택하세요.';
 
   @override
-  String get hostPhoneMustSelectUser =>
-      'The host phone must select at least one user.';
+  String get hostPhoneMustSelectUser => '호스트 기기는 사용자를 최소 한 명 선택해야 합니다.';
 
   @override
-  String get roomNoLongerInLobby => 'The room is no longer in the lobby.';
+  String get roomNoLongerInLobby => '방이 더 이상 대기실에 없습니다.';
 
   @override
-  String get completeUserSelectionToStart =>
-      'Complete user selection to start.';
+  String get completeUserSelectionToStart => '시작하려면 사용자 선택을 마치세요.';
 
   @override
-  String get preparingSecureRoom => 'Preparing the secure room';
+  String get preparingSecureRoom => '보안 방을 준비하는 중';
 
   @override
-  String get searchingNearbyBluetoothGames =>
-      'Searching nearby games over Bluetooth';
+  String get searchingNearbyBluetoothGames => '블루투스로 근처 게임을 찾는 중';
 
   @override
-  String get tapToJoin => 'Tap to join';
+  String get tapToJoin => '눌러서 참여하기';
 
   @override
   String get bluetoothLocationPermissionsRequired =>
-      'Bluetooth and location permissions are required to search for games.';
+      '게임을 찾으려면 블루투스와 위치 권한이 필요합니다.';
 
   @override
-  String get bluetoothLocationPermissionsShort =>
-      'Bluetooth and location permissions are required';
+  String get bluetoothLocationPermissionsShort => '블루투스와 위치 권한이 필요합니다';
 
   @override
-  String get couldNotStartSearch =>
-      'Could not start the search. Check Bluetooth and location.';
+  String get couldNotStartSearch => '검색을 시작할 수 없습니다. 블루투스와 위치를 확인하세요.';
 
   @override
   String couldNotConnectToHost(String host) {
-    return 'Could not connect to $host';
+    return '$host에 연결할 수 없습니다';
   }
 
   @override
   String get room => '방';
 
   @override
-  String get singleDeviceSubtitle => 'Game on this device';
+  String get singleDeviceSubtitle => '이 기기에서 진행';
 
   @override
   String get singleDeviceDescription =>
-      'Ideal for playing together by passing the phone around. Fast, direct setup.';
+      '휴대전화를 돌려 가며 함께 놀기에 좋습니다. 설정이 빠르고 간단합니다.';
 
   @override
-  String get multiDeviceSubtitle => 'Each player on their phone';
+  String get multiDeviceSubtitle => '각자 자기 휴대전화로';
 
   @override
   String get multiDeviceDescription =>
-      'Create a premium room, share the QR code and manage users from the lobby.';
+      '프리미엄 방을 만들고 QR 코드를 공유하며 대기실에서 사용자를 관리하세요.';
 
   @override
-  String get singleDeviceGameLabel => 'Game on this device';
+  String get singleDeviceGameLabel => '이 기기에서 하는 게임';
 
   @override
-  String get multiDeviceGameLabel => 'Multi-device game';
+  String get multiDeviceGameLabel => '여러 기기로 하는 게임';
 
   @override
-  String get mainDeviceUser => 'Main device user';
+  String get mainDeviceUser => '이 기기의 주 사용자';
 
   @override
-  String get couldNotCreateRoom =>
-      'Could not create the room. Check Bluetooth.';
+  String get couldNotCreateRoom => '방을 만들 수 없습니다. 블루투스를 확인하세요.';
 
   @override
   String cannotStartWithReason(String reason) {
-    return 'Cannot start: $reason';
+    return '시작할 수 없습니다: $reason';
   }
 
   @override
-  String get invalidRoom => 'invalid room';
+  String get invalidRoom => '잘못된 방';
 
   @override
   String get defaultPlayerName => '플레이어';
@@ -831,4 +824,46 @@ class AppLocalizationsKo extends AppLocalizations {
   String playerRejoined(String name) {
     return '$name 님이 게임에 복귀했습니다';
   }
+
+  @override
+  String get leaveGameTitle => '게임에서 나갈까요?';
+
+  @override
+  String get leaveGameSingleDevice => '진행 중인 게임이 사라지며 되돌릴 수 없습니다.';
+
+  @override
+  String get leaveGameHost => '당신은 호스트입니다. 나가면 모두의 게임이 끝납니다.';
+
+  @override
+  String get leaveGameClient => '게임에서 나갑니다. 호스트가 열어 두는 동안에는 다시 들어올 수 있습니다.';
+
+  @override
+  String get stayInGame => '계속 하기';
+
+  @override
+  String get permissionsNeededTitle => '필요한 권한';
+
+  @override
+  String get permissionsNeededBody => '멀티플레이 모드에는 다음 권한이 필요합니다:';
+
+  @override
+  String get openAppSettingsQuestion => '앱 설정을 열까요?';
+
+  @override
+  String get openSettings => '설정 열기';
+
+  @override
+  String get permissionLocation => '위치';
+
+  @override
+  String get permissionBluetoothAdvertise => '블루투스(광고)';
+
+  @override
+  String get permissionBluetoothConnect => '블루투스(연결)';
+
+  @override
+  String get permissionBluetoothScan => '블루투스(검색)';
+
+  @override
+  String get permissionNearbyWifi => '근처 Wi-Fi';
 }