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_fr.dart

@@ -1894,4 +1894,32 @@ class AppLocalizationsFr extends AppLocalizations {
 
   @override
   String get premiumActivo => 'Premium actif';
+
+  @override
+  String get premiumHojaTitulo => 'Débloquer PluriWave Premium';
+
+  @override
+  String get premiumBeneficioSinAnuncios =>
+      'Aucune publicité dans toute l\'application';
+
+  @override
+  String get premiumBeneficioAndroidAuto => 'Android Auto';
+
+  @override
+  String get premiumBeneficioGrabacion => 'Enregistrement des stations';
+
+  @override
+  String get premiumBeneficioVacaciones =>
+      'Périodes de vacances pour les alarmes';
+
+  @override
+  String get premiumBeneficioAlarmasIlimitadas =>
+      'Alarmes illimitées (la version gratuite en autorise jusqu\'à 5)';
+
+  @override
+  String get premiumPagoUnico =>
+      'Achat unique, pour toujours. Ce n\'est pas un abonnement.';
+
+  @override
+  String get premiumAhoraNo => 'Plus tard';
 }