Update and Delete activities are not forwarded

Looking at the code, the relay does not seem to handle `delete` or `status.update` events from the streaming server, which means that subscribing servers will be made aware of the first version of posts, but not updates or deletions.

Start by tracing the relay's event handling between the streaming server and subscribing servers, focusing on `delete` and `status.update` events. Compare their forwarding path with the existing first-version post handling, then verify that both event types reach subscribing servers with the expected activity data.

Written by the indexing model from the issue text.