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_hi.arb

@@ -246,28 +246,28 @@
   "release": "छोड़ें",
   "select": "चुनें",
   "delete": "हटाएँ",
-  "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": "शुरू करने के लिए कम से कम 3 उपयोगकर्ता चुनें।",
+  "hostPhoneMustSelectUser": "होस्ट फ़ोन को कम से कम एक उपयोगकर्ता चुनना होगा।",
+  "roomNoLongerInLobby": "कमरा अब लॉबी में नहीं है।",
+  "completeUserSelectionToStart": "शुरू करने के लिए उपयोगकर्ताओं का चयन पूरा करें।",
+  "preparingSecureRoom": "सुरक्षित कमरा तैयार किया जा रहा है",
+  "searchingNearbyBluetoothGames": "ब्लूटूथ से आस-पास के गेम खोजे जा रहे हैं",
+  "tapToJoin": "शामिल होने के लिए टैप करें",
+  "bluetoothLocationPermissionsRequired": "गेम खोजने के लिए ब्लूटूथ और लोकेशन की अनुमति चाहिए।",
+  "bluetoothLocationPermissionsShort": "ब्लूटूथ और लोकेशन की अनुमति चाहिए",
+  "couldNotStartSearch": "खोज शुरू नहीं हो सकी। ब्लूटूथ और लोकेशन जाँचें।",
+  "couldNotConnectToHost": "{host} से कनेक्ट नहीं हो सका",
   "room": "कक्ष",
-  "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": "इसी डिवाइस पर खेल",
+  "singleDeviceDescription": "फ़ोन एक-दूसरे को देकर साथ खेलने के लिए बढ़िया। सेटअप तेज़ और सीधा।",
+  "multiDeviceSubtitle": "हर खिलाड़ी अपने फ़ोन पर",
+  "multiDeviceDescription": "एक प्रीमियम कमरा बनाएँ, QR साझा करें और लॉबी से उपयोगकर्ता संभालें।",
+  "singleDeviceGameLabel": "इसी डिवाइस पर खेल",
+  "multiDeviceGameLabel": "मल्टी-डिवाइस खेल",
+  "mainDeviceUser": "डिवाइस का मुख्य उपयोगकर्ता",
+  "couldNotCreateRoom": "कमरा नहीं बन सका। ब्लूटूथ जाँचें।",
+  "cannotStartWithReason": "शुरू नहीं हो सकता: {reason}",
+  "invalidRoom": "अमान्य कमरा",
   "defaultPlayerName": "खिलाड़ी",
   "play": "खेलें",
   "history": "इतिहास",
@@ -368,5 +368,19 @@
   "reconnecting": "फिर से कनेक्ट हो रहा है...",
   "reconnectingHint": "होस्ट से कनेक्शन टूट गया। खेल में आपकी जगह सुरक्षित है।",
   "leaveGame": "खेल छोड़ें",
-  "playerRejoined": "{name} खेल में वापस आ गए"
+  "playerRejoined": "{name} खेल में वापस आ गए",
+  "leaveGameTitle": "खेल छोड़ना है?",
+  "leaveGameSingleDevice": "चल रहा खेल ख़त्म हो जाएगा और वापस नहीं मिलेगा।",
+  "leaveGameHost": "आप होस्ट हैं: आपके जाने पर सभी खिलाड़ियों का खेल ख़त्म हो जाएगा।",
+  "leaveGameClient": "आप खेल से बाहर निकल जाएँगे। जब तक होस्ट इसे खुला रखे, आप लौट सकते हैं।",
+  "stayInGame": "खेलते रहें",
+  "permissionsNeededTitle": "अनुमतियाँ चाहिए",
+  "permissionsNeededBody": "मल्टीप्लेयर मोड के लिए हमें चाहिए:",
+  "openAppSettingsQuestion": "क्या ऐप की सेटिंग खोलें?",
+  "openSettings": "सेटिंग खोलें",
+  "permissionLocation": "लोकेशन",
+  "permissionBluetoothAdvertise": "ब्लूटूथ (प्रसारण)",
+  "permissionBluetoothConnect": "ब्लूटूथ (कनेक्ट)",
+  "permissionBluetoothScan": "ब्लूटूथ (स्कैन)",
+  "permissionNearbyWifi": "आस-पास का वाई-फ़ाई"
 }