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_pt.dart

@@ -28,7 +28,7 @@ class AppLocalizationsPt extends AppLocalizations {
       'Sem medalhas novas desta vez. Continua a acumular fogo.';
 
   @override
-  String get calculatingRewards => 'Calculando recompensas...';
+  String get calculatingRewards => 'A calcular recompensas...';
 
   @override
   String get fireLabel => 'Fogo';
@@ -194,7 +194,7 @@ class AppLocalizationsPt extends AppLocalizations {
       'Certifique-se de que ninguém mais está olhando';
 
   @override
-  String get showingWord => '👁️ Mostrando...';
+  String get showingWord => '👁️ A mostrar...';
 
   @override
   String get holdToSee => '👆 Mantenha pressionado para ver';
@@ -263,7 +263,7 @@ class AppLocalizationsPt extends AppLocalizations {
   String get result => 'Resultado';
 
   @override
-  String get revealing => 'Revelando...';
+  String get revealing => 'A revelar...';
 
   @override
   String get wasImpostor => 'Era IMPOSTOR! 🎉';
@@ -845,4 +845,49 @@ class AppLocalizationsPt extends AppLocalizations {
   String playerRejoined(String name) {
     return '$name voltou ao jogo';
   }
+
+  @override
+  String get leaveGameTitle => 'Sair do jogo?';
+
+  @override
+  String get leaveGameSingleDevice =>
+      'O jogo em curso perde-se e não poderá ser recuperado.';
+
+  @override
+  String get leaveGameHost =>
+      'És o anfitrião: se saíres, o jogo termina para todos os jogadores.';
+
+  @override
+  String get leaveGameClient =>
+      'Vais sair do jogo. Podes voltar enquanto o anfitrião o mantiver aberto.';
+
+  @override
+  String get stayInGame => 'Continuar a jogar';
+
+  @override
+  String get permissionsNeededTitle => 'Permissões necessárias';
+
+  @override
+  String get permissionsNeededBody => 'Para o modo multijogador precisamos de:';
+
+  @override
+  String get openAppSettingsQuestion => 'Abrir as definições da aplicação?';
+
+  @override
+  String get openSettings => 'Abrir definições';
+
+  @override
+  String get permissionLocation => 'Localização';
+
+  @override
+  String get permissionBluetoothAdvertise => 'Bluetooth (anunciar)';
+
+  @override
+  String get permissionBluetoothConnect => 'Bluetooth (ligar)';
+
+  @override
+  String get permissionBluetoothScan => 'Bluetooth (procurar)';
+
+  @override
+  String get permissionNearbyWifi => 'Wi-Fi por perto';
 }