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/app_ar.arb

@@ -246,28 +246,28 @@
   "release": "تحرير",
   "select": "اختيار",
   "delete": "حذف",
-  "selectAtLeastThreeUsersToStart": "Select at least 3 users to start.",
-  "hostPhoneMustSelectUser": "The host phone must select at least one user.",
-  "roomNoLongerInLobby": "The room is no longer in the lobby.",
-  "completeUserSelectionToStart": "Complete user selection to start.",
-  "preparingSecureRoom": "Preparing the secure room",
-  "searchingNearbyBluetoothGames": "Searching nearby games over Bluetooth",
-  "tapToJoin": "Tap to join",
-  "bluetoothLocationPermissionsRequired": "Bluetooth and location permissions are required to search for games.",
-  "bluetoothLocationPermissionsShort": "Bluetooth and location permissions are required",
-  "couldNotStartSearch": "Could not start the search. Check Bluetooth and location.",
-  "couldNotConnectToHost": "Could not connect to {host}",
+  "selectAtLeastThreeUsersToStart": "اختر 3 مستخدمين على الأقل للبدء.",
+  "hostPhoneMustSelectUser": "يجب أن يختار هاتف المضيف مستخدمًا واحدًا على الأقل.",
+  "roomNoLongerInLobby": "لم تعد الغرفة في ردهة الانتظار.",
+  "completeUserSelectionToStart": "أكمل اختيار المستخدمين للبدء.",
+  "preparingSecureRoom": "جارٍ تجهيز الغرفة الآمنة",
+  "searchingNearbyBluetoothGames": "البحث عن جولات قريبة عبر البلوتوث",
+  "tapToJoin": "اضغط للانضمام",
+  "bluetoothLocationPermissionsRequired": "يلزم إذنا البلوتوث والموقع للبحث عن جولات.",
+  "bluetoothLocationPermissionsShort": "يلزم إذنا البلوتوث والموقع",
+  "couldNotStartSearch": "تعذّر بدء البحث. تحقق من البلوتوث والموقع.",
+  "couldNotConnectToHost": "تعذّر الاتصال بـ {host}",
   "room": "غرفة",
-  "singleDeviceSubtitle": "Game on this device",
-  "singleDeviceDescription": "Ideal for playing together by passing the phone around. Fast, direct setup.",
-  "multiDeviceSubtitle": "Each player on their phone",
-  "multiDeviceDescription": "Create a premium room, share the QR code and manage users from the lobby.",
-  "singleDeviceGameLabel": "Game on this device",
-  "multiDeviceGameLabel": "Multi-device game",
-  "mainDeviceUser": "Main device user",
-  "couldNotCreateRoom": "Could not create the room. Check Bluetooth.",
-  "cannotStartWithReason": "Cannot start: {reason}",
-  "invalidRoom": "invalid room",
+  "singleDeviceSubtitle": "اللعب على هذا الجهاز",
+  "singleDeviceDescription": "مثالي للعب معًا بتمرير الهاتف. إعداد سريع ومباشر.",
+  "multiDeviceSubtitle": "كل لاعب على هاتفه",
+  "multiDeviceDescription": "أنشئ غرفة مميزة، وشارك رمز QR، وأدر المستخدمين من ردهة الانتظار.",
+  "singleDeviceGameLabel": "اللعب على هذا الجهاز",
+  "multiDeviceGameLabel": "لعب متعدد الأجهزة",
+  "mainDeviceUser": "المستخدم الرئيسي للجهاز",
+  "couldNotCreateRoom": "تعذّر إنشاء الغرفة. تحقق من البلوتوث.",
+  "cannotStartWithReason": "تعذّر البدء: {reason}",
+  "invalidRoom": "غرفة غير صالحة",
   "defaultPlayerName": "لاعب",
   "play": "العب",
   "history": "السجل",
@@ -368,5 +368,19 @@
   "reconnecting": "جارٍ إعادة الاتصال...",
   "reconnectingHint": "انقطع الاتصال بالمضيف. مكانك في الجولة محفوظ.",
   "leaveGame": "مغادرة الجولة",
-  "playerRejoined": "عاد {name} إلى الجولة"
+  "playerRejoined": "عاد {name} إلى الجولة",
+  "leaveGameTitle": "هل تريد مغادرة الجولة؟",
+  "leaveGameSingleDevice": "ستفقد الجولة الجارية ولن يمكن استعادتها.",
+  "leaveGameHost": "أنت المضيف: إذا غادرت ستنتهي الجولة لجميع اللاعبين.",
+  "leaveGameClient": "ستغادر الجولة. يمكنك العودة ما دام المضيف يبقيها مفتوحة.",
+  "stayInGame": "متابعة اللعب",
+  "permissionsNeededTitle": "أذونات مطلوبة",
+  "permissionsNeededBody": "لوضع اللعب الجماعي نحتاج إلى:",
+  "openAppSettingsQuestion": "هل تريد فتح إعدادات التطبيق؟",
+  "openSettings": "فتح الإعدادات",
+  "permissionLocation": "الموقع",
+  "permissionBluetoothAdvertise": "بلوتوث (الإعلان)",
+  "permissionBluetoothConnect": "بلوتوث (الاتصال)",
+  "permissionBluetoothScan": "بلوتوث (المسح)",
+  "permissionNearbyWifi": "واي فاي قريب"
 }