/take?url=...&demo=true rendered with no key, no quota check and no metering,
because the handler read the demo flag from the caller's query string rather
than from the route. It was publicly reachable.
Fixed by reading the flag only from the route's own forced options. A privileged mode that can be requested is a parameter, not a mode.
The same change added the free-tier limits: three signups per IP per day, 30 free renders per target domain per minute, and a global budget of rendering time shared by all free and demo traffic. The smoke suite runs with billing off, which is why no test caught this, so a separate suite now boots with billing on.