fix(bienvenida,grabaciones): headline size, CTA radius, storage caption

Screen 14 / audit 14.3+14.7: welcome headline now 34px/ls-1.2 (was
headlineMedium's 28/ls-1.0), CTA restyled to a radius-18 rounded
rectangle instead of Material 3's default StadiumBorder (t4:696,715).

Screen 12 / audit 12.2+12.3: the recordings storage card now shows the
bold "X of Y used" headline ABOVE a 6px/radius-3 bar, followed by a
real folder-path + purge-policy caption below it -- was the bar first
with the "used" string as its only (small, generic) caption (t4:613).
New ARB key recordingsLibraryStorageFolderCaption, translated to all
13 locales.

Item 12.5 (folder/max-size settings living behind the header action
instead of inline on this screen) is a deliberate structural split
from WU15b; the audit itself scopes it out of this pass.

lib/l10n/gen/app_localizations.dart

@@ -880,6 +880,12 @@ abstract class AppLocalizations {
   /// **'{usedMb} MB de {totalMb} MB usados'**
   String recordingsLibraryStorageCaption(int usedMb, int totalMb);
 
+  /// No description provided for @recordingsLibraryStorageFolderCaption.
+  ///
+  /// In es, this message translates to:
+  /// **'Music/PluriWave · se borran las más antiguas al llegar al límite'**
+  String get recordingsLibraryStorageFolderCaption;
+
   /// No description provided for @recordingsLibraryEmptyTitle.
   ///
   /// In es, this message translates to:
@@ -1186,6 +1192,12 @@ abstract class AppLocalizations {
   /// **'Calidad mínima'**
   String get searchMinQualityFilterLabel;
 
+  /// No description provided for @searchLoadingStationsLabel.
+  ///
+  /// In es, this message translates to:
+  /// **'BUSCANDO EMISORAS…'**
+  String get searchLoadingStationsLabel;
+
   /// No description provided for @searchEmptyTitle.
   ///
   /// In es, this message translates to:
@@ -1198,6 +1210,12 @@ abstract class AppLocalizations {
   /// **'Sin resultados'**
   String get searchNoResultsTitle;
 
+  /// No description provided for @searchNoResultsForQueryTitle.
+  ///
+  /// In es, this message translates to:
+  /// **'Sin resultados para «{query}»'**
+  String searchNoResultsForQueryTitle(Object query);
+
   /// No description provided for @searchEmptySubtitle.
   ///
   /// In es, this message translates to:
@@ -1228,6 +1246,12 @@ abstract class AppLocalizations {
   /// **'Países'**
   String get countriesScreenTitle;
 
+  /// No description provided for @countriesSearchHint.
+  ///
+  /// In es, this message translates to:
+  /// **'País o código...'**
+  String get countriesSearchHint;
+
   /// No description provided for @countriesYourLanguagesTitle.
   ///
   /// In es, this message translates to:
@@ -1882,6 +1906,12 @@ abstract class AppLocalizations {
   /// **'{minutes} min'**
   String alarmSnoozeOptionLabel(int minutes);
 
+  /// No description provided for @alarmSnoozeUsualLabel.
+  ///
+  /// In es, this message translates to:
+  /// **'habitual'**
+  String get alarmSnoozeUsualLabel;
+
   /// No description provided for @saveFavoritesAlarmHint.
   ///
   /// In es, this message translates to:
@@ -2462,6 +2492,12 @@ abstract class AppLocalizations {
   /// **'Días: {days}'**
   String alarmScheduleWeekdays(Object days);
 
+  /// No description provided for @alarmRepeatSectionLabel.
+  ///
+  /// In es, this message translates to:
+  /// **'REPETIR'**
+  String get alarmRepeatSectionLabel;
+
   /// No description provided for @androidReliabilityTitle.
   ///
   /// In es, this message translates to: