auto-save code when users are logged out?

# TL;DR
If your login times out while editing a study, the current system allows you to continue editing study code, but when you try to save, it will redirect you to the login page and all your changes/code will actually be lost.

# Narrative
It would be nice if, when you get auto-booted out after 24 hours, the website would also auto-save your study if you are currently editing your code. The work-around is of course just logging out and logging back in every morning (rendering this feature very much not critical). The pain comes in if you forget to do that, and then in the middle of making a bunch of edits you get auto-logged out. You will be able to continue making changes to your code, even if you have been logged out. But you will not be able to save them, because when you try you will be redirected to log in again, and nothing you did will be saved.

# Acceptance Criteria
A precise description of how/when this issue will be considered closed, e.g.:

- if studies in edit mode auto-save right before your login times out, or if some other feature is invented that prevents this issue.

# Implementation Notes
You are the experts and I don't really know if what I suggested is reasonable :)

No file or test is named. Start by tracing the study editing and save flow alongside the 24-hour login timeout behavior, then reproduce an edit followed by session expiry. Done means edits made near timeout are preserved through logout, either by saving before expiry or by another accepted recovery path.

Written by the indexing model from the issue text.