4a992646

By: Michael Lynch <git@mtlynch.io>

Extract token entry creation into login_token.Generator

Move login token creation logic out of magiclogin.NewSender into a
login_token.Generator type, removing the NowFunc parameter and
LoginTokenExpiry constant from the magiclogin package.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>