User info in Nephthys

I think it would be helpful for helpers if we could see user information in the support channel.

My suggested implementation of this would be to have either a macro that sends an ephemeral message, or a button that opens a modal only accessible to helpers.

The data should be fetched from an API endpoint that can be in the transcript file. This should also be fully optional for programs to use.

This is an example of what we had for High Seas with Boatswain

Start by reviewing the existing support-channel flow and the transcript file mentioned as a possible location for the API endpoint. Clarify whether the project should use an ephemeral message or helper-only modal, then define the optional behavior and the user information that must be returned.

Written by the indexing model from the issue text.