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/app_ja.arb

@@ -262,8 +262,11 @@
   "searchCountryFilterLabel": "国",
   "searchLanguageFilterLabel": "言語",
   "searchMinQualityFilterLabel": "最低品質",
+  "searchLoadingStationsLabel": "局を検索中…",
   "searchEmptyTitle": "局を検索",
   "searchNoResultsTitle": "結果がありません",
+  "searchNoResultsForQueryTitle": "「{query}」の結果はありません",
+  "@searchNoResultsForQueryTitle": {"placeholders": {"query": {}}},
   "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。",
   "searchNoResultsSubtitle": "有効な電波を見つけるには、フィルターを外すか別の名前を入力してください。",
   "countrySpain": "スペイン",
@@ -440,6 +443,7 @@
       }
     }
   },
+  "alarmSnoozeUsualLabel": "通常",
   "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。",
   "useCurrentStationAction": "現在の局を使用",
   "playDuringVacations": "休暇中も鳴らす",
@@ -589,6 +593,7 @@
       "days": {}
     }
   },
+  "alarmRepeatSectionLabel": "繰り返し",
   "androidReliabilityTitle": "Androidの信頼性を確認",
   "closeAction": "閉じる",
   "customOption": "カスタム",
@@ -705,6 +710,7 @@
   "alarmVolumeRisingStatus": "音量を上げています",
   "countriesAllTitle": "すべての国",
   "countriesScreenTitle": "国",
+  "countriesSearchHint": "国名またはコード...",
   "countriesYourLanguagesTitle": "あなたの言語",
   "customStationsAddCta": "カスタム局を追加",
   "equalizerActiveOutputDefault": "この端末のスピーカー",
@@ -746,6 +752,7 @@
   "recordingRenameEmptyError": "名前を入力してください",
   "recordingRenameLabel": "名前",
   "recordingsLibraryEmptySubtitle": "保存した録音はここに表示されます。",
+  "recordingsLibraryStorageFolderCaption": "Music/PluriWave・上限に達すると古い順に削除されます",
   "recordingsLibraryEmptyTitle": "まだ録音がありません",
   "recordingsLibrarySettingsTooltip": "録音設定",
   "recordingsLibraryStorageCaption": "{totalMb} MB 中 {usedMb} MB 使用済み",