iOS transfers: 'Uploading...' then 'Uploaded' notification, and count share uploads

The Share Extension's session had no delegate, so a fast upload finished
unseen and the invalidated session was discarded before the app could hear of
it - no summary notification. Results are now handled by a shared delegate in
whichever process is alive, started/finished notifications replace each
other in place, and the app refreshes the folder the extension uploaded to.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

ios/Runner/Native/NativeServices.swift

@@ -125,6 +125,7 @@ enum NativeServices {
     NotificationCenter.default.addObserver(
       forName: UIApplication.didBecomeActiveNotification, object: nil, queue: .main
     ) { _ in
+      TransferManager.shared.deliverExtensionUploads()
       guard let sink = shareEvents.sink else { return }
       let items = consumeShared()
       if !items.isEmpty { sink(items.map(encode)) }