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_palabras_cliente.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:farolero/tema/dialogo_confirmacion.dart';
 import 'package:farolero/l10n/generated/app_localizations.dart';
 import 'package:farolero/modelos/inicio_partida_multijugador.dart';
 import 'package:farolero/tema/componentes_farolero.dart';
@@ -10,11 +11,16 @@ class PantallaPalabrasCliente extends StatefulWidget {
   final String? pistaImpostor;
   final VoidCallback onTodosVistos;
 
+  /// El host abre esta pantalla desde el gestor: allí el atrás solo
+  /// debe cerrarla, no ofrecer abandonar la partida.
+  final bool protegerSalida;
+
   const PantallaPalabrasCliente({
     super.key,
     required this.jugadores,
     this.pistaImpostor,
     required this.onTodosVistos,
+    this.protegerSalida = true,
   });
 
   @override
@@ -47,7 +53,10 @@ class _PantallaPalabrasClienteState extends State<PantallaPalabrasCliente> {
     final l10n = AppLocalizations.of(context)!;
     final actual = _actual;
 
-    return Scaffold(
+    return GuardiaSalidaPartida(
+      contexto: ContextoSalida.cliente,
+      activo: widget.protegerSalida,
+      child: Scaffold(
       body: FondoFarolero(
         intenso: true,
         child: SafeArea(
@@ -147,6 +156,7 @@ class _PantallaPalabrasClienteState extends State<PantallaPalabrasCliente> {
         ),
       ),
       ),
+    ),
     );
   }
 }