zeromind.setCover

Set a published world's cover image — the picture people see in listings before they open it. Point it at an image in this world's VFS and the bytes are uploaded and stamped in one call; a capture.viewport shot written to a path is the usual source. Pass blobSha256 instead to stamp an already-uploaded blob without re-uploading.

Needs Publish scope to upload and Maintainer access to stamp.