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_de.dart

@@ -1888,4 +1888,29 @@ class AppLocalizationsDe extends AppLocalizations {
 
   @override
   String get premiumActivo => 'Premium aktiv';
+
+  @override
+  String get premiumHojaTitulo => 'PluriWave Premium freischalten';
+
+  @override
+  String get premiumBeneficioSinAnuncios => 'Keine Werbung in der gesamten App';
+
+  @override
+  String get premiumBeneficioAndroidAuto => 'Android Auto';
+
+  @override
+  String get premiumBeneficioGrabacion => 'Sender aufnehmen';
+
+  @override
+  String get premiumBeneficioVacaciones => 'Urlaubszeiträume für Wecker';
+
+  @override
+  String get premiumBeneficioAlarmasIlimitadas =>
+      'Unbegrenzte Wecker (die kostenlose Version erlaubt bis zu 5)';
+
+  @override
+  String get premiumPagoUnico => 'Einmalzahlung, für immer. Kein Abonnement.';
+
+  @override
+  String get premiumAhoraNo => 'Nicht jetzt';
 }