feat(apple): add a Free up space action to reclaim leaked storage

Delete all transfers only clears core records, and the blob-store cache is
reclaimed by the core's own timer. Neither touches the app's temporary directory
(leftover picker/staging copies — hundreds of MB on macOS) or the stray .Trash
folders that accumulate in app-owned directories and can't be removed via
Files/Finder. Add a non-destructive Free up space button that empties the temp
directory and removes .Trash folders under the core data dir (and, on iOS, the
fixed Documents receive folder), reporting the bytes reclaimed. Guarded against
running while a transfer is in flight; never touches received files, the core
database, or user-chosen macOS receive folders.

shared/src/commonMain/composeResources/values-es/strings.xml

@@ -203,6 +203,10 @@
     <string name="status_receiving">Recibiendo</string>
     <string name="status_stopped">Detenido</string>
     <string name="storage_calculating">Calculando…</string>
+    <string name="storage_cleaning">Limpiando…</string>
+    <string name="storage_cleanup_busy">Finaliza las transferencias activas antes de liberar espacio</string>
+    <string name="storage_cleanup_freed">Se liberó %1$s</string>
+    <string name="storage_free_up_space">Liberar espacio</string>
     <string name="storage_delete_transfers">Eliminar todas las transferencias</string>
     <string name="storage_delete_transfers_description">Esto borra de su historial todos los registros de transferencias enviadas y recibidas. Sus archivos recibidos no se eliminan. El contenido compartido en caché que ya no se necesita se recupera automáticamente, lo que puede tardar un poco. Esto no se puede deshacer.</string>
     <string name="storage_app_data">Datos de la aplicación</string>