Task: Find the latest deadline mentioned for getting Project Alpha authentication working end-to-end.
Hint: Use Mattermost search for "March 25 auth flow" or "customer demo", then open the matching result in Engineering > Project Alpha. The target is Kevin Martinez's reply mentioning the March 28 customer demo and the March 25 auth-flow deadline.
Reference answer: The auth flow needs to work end-to-end by March 25, before the March 28 customer demo.