Sign-in pages skip needless checks and load quicker

The sign-in and sign-up pages now boot faster by skipping a check they never needed.

On every page load, the app was asking the server "who is this?", sometimes twice. On the authentication pages that question is pointless: those pages are only ever shown to signed-out visitors, so the answer is always "nobody". Each of those round-trips added a few hundred milliseconds of waiting for nothing.

We removed a duplicate check entirely and taught the sign-in pages to skip the lookup, while still confirming your session the rare time a logged-in user lands there and needs to be sent onward.

Less invisible busywork at startup means the doors to your account open a little quicker.