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/pantallas/pantalla_resultado_online.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import '../tema/dialogo_confirmacion.dart';
 import 'package:farolero/l10n/generated/app_localizations.dart';
 import '../modelos/inicio_partida_multijugador.dart';
 import '../modelos/snapshot_partida_online.dart';
@@ -158,30 +159,33 @@ class _PantallaResultadoOnlineState extends State<PantallaResultadoOnline> {
     final l10n = AppLocalizations.of(context)!;
     final resultado = _snapshot.resultadoActual;
 
-    return Scaffold(
-      backgroundColor: TemaApp.colorFondo,
-      appBar: AppBar(
-        title: Text(_snapshot.fase == 'adivinanza'
-            ? l10n.impostorGuessTitle
-            : l10n.result),
-        automaticallyImplyLeading: false,
-        backgroundColor: Colors.transparent,
-        elevation: 0,
-        actions: _acciones(context, l10n),
-      ),
-      body: FondoFarolero(
-        intenso: true,
-        child: SafeArea(
-          top: false,
-          child: SingleChildScrollView(
-            padding: const EdgeInsets.all(24),
-            child: resultado == null
-                ? _buildEsperaAdivinanza(context, l10n)
-                : ResultadoRondaFarolero(
-                    resultado: resultado,
-                    jugadores: _snapshot.jugadores,
-                    mensaje: _snapshot.mensaje,
-                  ),
+    return GuardiaSalidaPartida(
+      contexto: ContextoSalida.cliente,
+      child: Scaffold(
+        backgroundColor: TemaApp.colorFondo,
+        appBar: AppBar(
+          title: Text(_snapshot.fase == 'adivinanza'
+              ? l10n.impostorGuessTitle
+              : l10n.result),
+          automaticallyImplyLeading: false,
+          backgroundColor: Colors.transparent,
+          elevation: 0,
+          actions: _acciones(context, l10n),
+        ),
+        body: FondoFarolero(
+          intenso: true,
+          child: SafeArea(
+            top: false,
+            child: SingleChildScrollView(
+              padding: const EdgeInsets.all(24),
+              child: resultado == null
+                  ? _buildEsperaAdivinanza(context, l10n)
+                  : ResultadoRondaFarolero(
+                      resultado: resultado,
+                      jugadores: _snapshot.jugadores,
+                      mensaje: _snapshot.mensaje,
+                    ),
+            ),
           ),
         ),
       ),