Sign-in page now loads dramatically faster

Our auth system was being imported and initialized at the very top of every page bundle — including the sign-in page itself, where it isn't needed until the user actually submits the form.

That meant about 150KB of auth code was being downloaded, parsed, and executed before the sign-in form could even respond to typing. It was the single biggest slice keeping the sign-in page's responsiveness around 340ms.

The auth library now loads on demand, the first time any code path actually needs it. The sign-in page renders instantly, and the auth module loads quietly in the background while you're typing your email.

This is the kind of perf work that has no visible feature attached but every user feels every day. The new sign-in flow should feel noticeably snappier.