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_ja.dart

@@ -431,6 +431,10 @@ class AppLocalizationsJa extends AppLocalizations {
     return '$totalMb MB 中 $usedMb MB 使用済み';
   }
 
+  @override
+  String get recordingsLibraryStorageFolderCaption =>
+      'Music/PluriWave・上限に達すると古い順に削除されます';
+
   @override
   String get recordingsLibraryEmptyTitle => 'まだ録音がありません';
 
@@ -594,12 +598,20 @@ class AppLocalizationsJa extends AppLocalizations {
   @override
   String get searchMinQualityFilterLabel => '最低品質';
 
+  @override
+  String get searchLoadingStationsLabel => '局を検索中…';
+
   @override
   String get searchEmptyTitle => '局を検索';
 
   @override
   String get searchNoResultsTitle => '結果がありません';
 
+  @override
+  String searchNoResultsForQueryTitle(Object query) {
+    return '「$query」の結果はありません';
+  }
+
   @override
   String get searchEmptySubtitle => '上部バーやチップを使って、世界中の電波を見つけましょう。';
 
@@ -630,6 +642,9 @@ class AppLocalizationsJa extends AppLocalizations {
   @override
   String get countriesScreenTitle => '国';
 
+  @override
+  String get countriesSearchHint => '国名またはコード...';
+
   @override
   String get countriesYourLanguagesTitle => 'あなたの言語';
 
@@ -985,6 +1000,9 @@ class AppLocalizationsJa extends AppLocalizations {
     return '$minutes分';
   }
 
+  @override
+  String get alarmSnoozeUsualLabel => '通常';
+
   @override
   String get saveFavoritesAlarmHint => '音楽アラームとして使うには、局をお気に入りに保存してください。';
 
@@ -1312,6 +1330,9 @@ class AppLocalizationsJa extends AppLocalizations {
     return '曜日: $days';
   }
 
+  @override
+  String get alarmRepeatSectionLabel => '繰り返し';
+
   @override
   String get androidReliabilityTitle => 'Androidの信頼性を確認';