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_gestor_host.dart

@@ -1,4 +1,5 @@
 import 'dart:async';
+import '../tema/dialogo_confirmacion.dart';
 import 'dart:math';
 import 'package:flutter/material.dart';
 import 'package:farolero/l10n/generated/app_localizations.dart';
@@ -257,7 +258,9 @@ class _PantallaGestorHostState extends State<PantallaGestorHost> {
         clientesPendientes.every((id) => _clientesListos[id] == true);
     final todosVotaron = estado.todosHanVotado();
 
-    return Scaffold(
+    return GuardiaSalidaPartida(
+      contexto: ContextoSalida.host,
+      child: Scaffold(
       appBar: AppBar(
         title: Text(l10n.hostGame),
         automaticallyImplyLeading: false,
@@ -299,8 +302,15 @@ class _PantallaGestorHostState extends State<PantallaGestorHost> {
                     ),
           ),
           IconButton(
+            tooltip: l10n.leaveGame,
             icon: IconoFarolero(Icons.close),
             onPressed: () async {
+              if (!await confirmarSalirDePartida(
+                context,
+                ContextoSalida.host,
+              )) {
+                return;
+              }
               await nearby.desconectar();
               widget.onPartidaFin();
             },
@@ -340,6 +350,7 @@ class _PantallaGestorHostState extends State<PantallaGestorHost> {
           ),
         ),
       ),
+    ),
     );
   }
 
@@ -580,6 +591,7 @@ class _PantallaGestorHostState extends State<PantallaGestorHost> {
         context,
         MaterialPageRoute(
           builder: (_) => PantallaPalabrasCliente(
+            protegerSalida: false,
             jugadores: jugadoresHost,
             pistaImpostor: partida.config.pistaImpostor
                 ? partida.pistaImpostor
@@ -863,6 +875,7 @@ class _PantallaGestorHostState extends State<PantallaGestorHost> {
       context,
       MaterialPageRoute(
         builder: (_) => PantallaVotacionCliente(
+          protegerSalida: false,
           jugadores: partida.jugadoresActivos,
           jugadoresControlados: jugadoresHost,
           partidaId: context.read<ServicioNearby>().roomId,