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_en.dart

@@ -443,6 +443,10 @@ class AppLocalizationsEn extends AppLocalizations {
     return '$usedMb MB of $totalMb MB used';
   }
 
+  @override
+  String get recordingsLibraryStorageFolderCaption =>
+      'Music/PluriWave · purges oldest at limit';
+
   @override
   String get recordingsLibraryEmptyTitle => 'No recordings yet';
 
@@ -615,12 +619,20 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get searchMinQualityFilterLabel => 'Minimum quality';
 
+  @override
+  String get searchLoadingStationsLabel => 'SEARCHING FOR STATIONS…';
+
   @override
   String get searchEmptyTitle => 'Search for a station';
 
   @override
   String get searchNoResultsTitle => 'No results';
 
+  @override
+  String searchNoResultsForQueryTitle(Object query) {
+    return 'No results for \"$query\"';
+  }
+
   @override
   String get searchEmptySubtitle =>
       'Use the top bar or chips to discover stations from around the world.';
@@ -654,6 +666,9 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get countriesScreenTitle => 'Countries';
 
+  @override
+  String get countriesSearchHint => 'Country or code...';
+
   @override
   String get countriesYourLanguagesTitle => 'Your languages';
 
@@ -1014,6 +1029,9 @@ class AppLocalizationsEn extends AppLocalizations {
     return '$minutes min';
   }
 
+  @override
+  String get alarmSnoozeUsualLabel => 'usual';
+
   @override
   String get saveFavoritesAlarmHint =>
       'Save stations in Favorites to use them as a music alarm.';
@@ -1352,6 +1370,9 @@ class AppLocalizationsEn extends AppLocalizations {
     return 'Days: $days';
   }
 
+  @override
+  String get alarmRepeatSectionLabel => 'REPEAT';
+
   @override
   String get androidReliabilityTitle => 'Review Android reliability';