Investigate using `ActiveSupport::CurrentAttributes`

`ActiveSupport::CurrentAttributes` is the new cool way to do request-specific attributes like our `current_user` and `current_session`

https://api.rubyonrails.org/classes/ActiveSupport/CurrentAttributes.html

Start by reading the linked ActiveSupport::CurrentAttributes documentation, then locate the existing implementations of current_user and current_session. The issue does not name files, tests, migration boundaries, or acceptance criteria, so completion would require defining whether and how those request-specific attributes should be migrated.

Written by the indexing model from the issue text.