RequireAuth now sends a logged-out GET to /pages/login with its path
and query in a `next` parameter. The login form carries it as a hidden
field, and a successful login redirects there when it is a path on
this site; anything else, plain or percent-encoded, goes to `/`, which
leads to the webhook list. A browser already logged in that opens the
login page goes to the same place. The navigation bar on the login
page no longer links to the login page.
Model: opus-5-5