filer: read a pending remote rename copy from the source key

A remote-only rename over a remote-only target commits before its copy
lands, so reads on the new path served the target's old object until the
copy stamped the entry — and indefinitely when the copy failed without
remote.sync running. The committed entry now records the renamed-from
path, and remote-only reads resolve that object's key while the stamp
is pending; the copy's stamp and the sync's completion stamp both clear
the marker.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

weed/command/filer_remote_sync_dir.go

@@ -658,6 +658,7 @@ func updateLocalEntry(filerClient filer_pb.FilerClient, dir string, entry *filer
 	remoteEntry.LastLocalSyncTsNs = time.Now().UnixNano()
 	expected := proto.Clone(entry).(*filer_pb.Entry)
 	entry.RemoteEntry = remoteEntry
+	delete(entry.Extended, filer.ExtRemoteRenameSourceKey)
 	err := filerClient.WithFilerClient(false, func(client filer_pb.SeaweedFilerClient) error {
 		_, err := client.UpdateEntry(context.Background(), &filer_pb.UpdateEntryRequest{
 			Directory: dir,