Handle POST requests differently (ie don't "forget" them during sudo-auth step)

One slightly unfortunate feature of the current implementation is that POST requests just get swallowed/ignored by the interposition of the sudo authentication page.

Use case: a user can load a copy of a "secure" page, and keep it open in a browser tab for long enough that their sudo cookie expires (maybe they loaded it 2hrs59 mins after login, or maybe they just left the tab open for a long time). By the time they submit the form on that page, they are asked to re-authenticate, and on success they are redirected back to where they were, but the post request is forgotten.

Ideally there would be some magic for "saving" the post request, and then re-submitting it on successful auth. That might be a little tricky to implement mind you. A second-best / fallback would be to at least be able to display a message to the user saying they'll have to re-submit the request...

No files, tests, or entry points are identified. Begin by locating the sudo-auth interposition and its handling of POST requests; determine whether successful authentication can preserve and resubmit the request or should show a re-submit message. Done means the chosen behavior is covered for an expired sudo cookie.