feat(apple): streamline the Storage screen and fix stuck usage

Redesign the Storage screen for clarity: an "On this device" usage header with a
manual Refresh control, symbol-led action buttons, and a caption under each action
spelling out exactly what it does (Free up space = temp + trash, non-destructive;
Delete all transfers = clears history + cached share content, keeps received
files).

Fix the summary sticking on "Calculating…": it loaded only on .onAppear and bailed
when opened before the core finished its async launch, leaving the loading branch
showing with nothing running (only a manual refresh recovered it). loadStorageUsage
now waits for the core to become ready before reading usage, distinguishes a real
failure (retry) from loading, loads via .task, and can be refreshed on demand. Use
plain button styling with explicit tints so pressing an action no longer flips the
label to the white selection highlight.

localization/strings.json

@@ -3188,6 +3188,76 @@
         "ru": "Освобождено {size}"
       }
     },
+    "storage_delete_transfers_caption": {
+      "context": "Settings > Storage: caption under the destructive delete-all button.",
+      "translations": {
+        "en": "Clears your send and receive history and the app's cached share content. Received files on disk are kept.",
+        "fr": "Efface votre historique d'envois et de réceptions ainsi que le contenu de partage mis en cache par l'app. Les fichiers reçus sur le disque sont conservés.",
+        "es": "Borra tu historial de envíos y recepciones y el contenido compartido en caché de la app. Los archivos recibidos en el disco se conservan.",
+        "it": "Cancella la cronologia di invii e ricezioni e i contenuti di condivisione memorizzati dall'app. I file ricevuti sul disco vengono mantenuti.",
+        "de": "Löscht deinen Sende- und Empfangsverlauf sowie die zwischengespeicherten Freigabeinhalte der App. Empfangene Dateien auf dem Datenträger bleiben erhalten.",
+        "pt": "Limpa o teu histórico de envios e receções e o conteúdo de partilha em cache da app. Os ficheiros recebidos no disco são mantidos.",
+        "pl": "Czyści historię wysyłania i odbierania oraz zapisane w pamięci podręcznej udostępniane treści. Odebrane pliki na dysku zostają zachowane.",
+        "nl": "Wist je verzend- en ontvangstgeschiedenis en de gecachte deelinhoud van de app. Ontvangen bestanden op schijf blijven behouden.",
+        "ru": "Очищает историю отправки и получения и кэшированное содержимое общих ресурсов. Полученные файлы на диске сохраняются."
+      }
+    },
+    "storage_free_up_space_caption": {
+      "context": "Settings > Storage: caption under the free-up-space button.",
+      "translations": {
+        "en": "Removes temporary files and leftover trash from earlier transfers. Your transfers and received files are kept.",
+        "fr": "Supprime les fichiers temporaires et les résidus des transferts précédents. Vos transferts et fichiers reçus sont conservés.",
+        "es": "Elimina los archivos temporales y los restos de transferencias anteriores. Tus transferencias y archivos recibidos se conservan.",
+        "it": "Rimuove i file temporanei e i residui dei trasferimenti precedenti. I tuoi trasferimenti e i file ricevuti vengono mantenuti.",
+        "de": "Entfernt temporäre Dateien und Reste früherer Übertragungen. Deine Übertragungen und empfangenen Dateien bleiben erhalten.",
+        "pt": "Remove ficheiros temporários e resíduos de transferências anteriores. As tuas transferências e ficheiros recebidos são mantidos.",
+        "pl": "Usuwa pliki tymczasowe i pozostałości po wcześniejszych transferach. Twoje transfery i odebrane pliki zostają zachowane.",
+        "nl": "Verwijdert tijdelijke bestanden en resten van eerdere overdrachten. Je overdrachten en ontvangen bestanden blijven behouden.",
+        "ru": "Удаляет временные файлы и остатки прошлых передач. Ваши передачи и полученные файлы сохраняются."
+      }
+    },
+    "storage_refresh": {
+      "context": "Settings > Storage: label for the button that recalculates usage.",
+      "translations": {
+        "en": "Refresh",
+        "fr": "Actualiser",
+        "es": "Actualizar",
+        "it": "Aggiorna",
+        "de": "Aktualisieren",
+        "pt": "Atualizar",
+        "pl": "Odśwież",
+        "nl": "Vernieuwen",
+        "ru": "Обновить"
+      }
+    },
+    "storage_unavailable": {
+      "context": "Settings > Storage: shown when usage couldn't be calculated yet.",
+      "translations": {
+        "en": "Storage usage isn't available yet",
+        "fr": "L'utilisation du stockage n'est pas encore disponible",
+        "es": "El uso de almacenamiento aún no está disponible",
+        "it": "L'utilizzo dello spazio non è ancora disponibile",
+        "de": "Die Speichernutzung ist noch nicht verfügbar",
+        "pt": "A utilização do armazenamento ainda não está disponível",
+        "pl": "Wykorzystanie pamięci nie jest jeszcze dostępne",
+        "nl": "Opslaggebruik is nog niet beschikbaar",
+        "ru": "Данные об использовании хранилища пока недоступны"
+      }
+    },
+    "storage_usage_header": {
+      "context": "Settings > Storage: header above the usage breakdown.",
+      "translations": {
+        "en": "On this device",
+        "fr": "Sur cet appareil",
+        "es": "En este dispositivo",
+        "it": "Su questo dispositivo",
+        "de": "Auf diesem Gerät",
+        "pt": "Neste dispositivo",
+        "pl": "Na tym urządzeniu",
+        "nl": "Op dit apparaat",
+        "ru": "На этом устройстве"
+      }
+    },
     "storage_free_up_space": {
       "context": "Settings > Storage: button that clears temporary files and stray trash.",
       "translations": {