fix(paywall): add dismiss controls and honest premium copy

The premium sheet had no close affordance or way to defer, and its
copy only said "Función Premium" without stating what it unlocks.
Adds a header close (X) button and a "not now" secondary action so
dismissal is never harder than purchasing, and replaces the bare
title with a concrete, honest breakdown of the 5 things premium
unlocks (no ads, Android Auto, station recording, alarm vacation
ranges, unlimited alarms) plus the one-time-purchase framing. The
phone equalizer is never listed, since it stays free for everyone.
New l10n keys added to all 13 locales.

lib/l10n/gen/app_localizations_ru.dart

@@ -1884,4 +1884,31 @@ class AppLocalizationsRu extends AppLocalizations {
 
   @override
   String get premiumActivo => 'Премиум активен';
+
+  @override
+  String get premiumHojaTitulo => 'Разблокировать PluriWave Premium';
+
+  @override
+  String get premiumBeneficioSinAnuncios =>
+      'Никакой рекламы во всём приложении';
+
+  @override
+  String get premiumBeneficioAndroidAuto => 'Android Auto';
+
+  @override
+  String get premiumBeneficioGrabacion => 'Запись радиостанций';
+
+  @override
+  String get premiumBeneficioVacaciones => 'Периоды отпуска для будильников';
+
+  @override
+  String get premiumBeneficioAlarmasIlimitadas =>
+      'Неограниченное количество будильников (бесплатный план позволяет до 5)';
+
+  @override
+  String get premiumPagoUnico =>
+      'Единоразовая покупка, навсегда. Это не подписка.';
+
+  @override
+  String get premiumAhoraNo => 'Не сейчас';
 }