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_eu.arb

@@ -246,28 +246,28 @@
   "release": "Askatu",
   "select": "Hautatu",
   "delete": "Ezabatu",
-  "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": "Hautatu gutxienez 3 erabiltzaile hasteko.",
+  "hostPhoneMustSelectUser": "Ostalariaren mugikorrak gutxienez erabiltzaile bat hautatu behar du.",
+  "roomNoLongerInLobby": "Gela jada ez dago lobbyan.",
+  "completeUserSelectionToStart": "Osatu erabiltzaileen hautaketa hasteko.",
+  "preparingSecureRoom": "Gela segurua prestatzen",
+  "searchingNearbyBluetoothGames": "Inguruko partidak bilatzen Bluetooth bidez",
+  "tapToJoin": "Sakatu batzeko",
+  "bluetoothLocationPermissionsRequired": "Bluetooth eta kokapen baimenak behar dira partidak bilatzeko.",
+  "bluetoothLocationPermissionsShort": "Bluetooth eta kokapen baimenak behar dira",
+  "couldNotStartSearch": "Ezin izan da bilaketa hasi. Egiaztatu Bluetooth eta kokapena.",
+  "couldNotConnectToHost": "Ezin izan da {host}(e)ra konektatu",
   "room": "Gela",
-  "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": "Partida gailu honetan",
+  "singleDeviceDescription": "Ezin hobea denok elkarrekin jokatzeko mugikorra pasatuz. Konfigurazio azkarra eta zuzena.",
+  "multiDeviceSubtitle": "Jokalari bakoitza bere mugikorrean",
+  "multiDeviceDescription": "Sortu gela premium bat, partekatu QR kodea eta kudeatu erabiltzaileak lobbytik.",
+  "singleDeviceGameLabel": "Partida gailu honetan",
+  "multiDeviceGameLabel": "Gailu anitzeko partida",
+  "mainDeviceUser": "Gailuaren erabiltzaile nagusia",
+  "couldNotCreateRoom": "Ezin izan da gela sortu. Egiaztatu Bluetooth.",
+  "cannotStartWithReason": "Ezin da hasi: {reason}",
+  "invalidRoom": "gela baliogabea",
   "defaultPlayerName": "Jokalaria",
   "play": "Jokatu",
   "history": "Historia",
@@ -368,5 +368,19 @@
   "reconnecting": "Berriz konektatzen...",
   "reconnectingHint": "Ostalariarekiko konexioa galdu da. Partidan duzun lekua gordeta dago.",
   "leaveGame": "Partidatik irten",
-  "playerRejoined": "{name} partidara itzuli da"
+  "playerRejoined": "{name} partidara itzuli da",
+  "leaveGameTitle": "Partidatik irten nahi duzu?",
+  "leaveGameSingleDevice": "Abian den partida galduko da eta ezin izango duzu berreskuratu.",
+  "leaveGameHost": "Zu zara ostalaria: irtenez gero, partida jokalari guztientzat amaituko da.",
+  "leaveGameClient": "Partidatik aterako zara. Itzuli ahal izango zara ostalariak zabalik mantentzen duen bitartean.",
+  "stayInGame": "Jokatzen jarraitu",
+  "permissionsNeededTitle": "Baimenak behar dira",
+  "permissionsNeededBody": "Jokalari anitzeko modurako hau behar dugu:",
+  "openAppSettingsQuestion": "Aplikazioaren ezarpenak ireki nahi dituzu?",
+  "openSettings": "Ireki ezarpenak",
+  "permissionLocation": "Kokapena",
+  "permissionBluetoothAdvertise": "Bluetooth (iragarri)",
+  "permissionBluetoothConnect": "Bluetooth (konektatu)",
+  "permissionBluetoothScan": "Bluetooth (eskaneatu)",
+  "permissionNearbyWifi": "Inguruko Wi-Fi"
 }