Honest funnel rates on cookieless sites

On cookieless tracking, visitor ids rotate every UTC day. A visitor-scoped funnel with a week-long window cannot complete across midnight, but the chart used to show a confident conversion rate with no explanation.

That combination is now rejected when you create or edit a funnel. Existing funnels that already have it get a clear Conversion floor caveat and a caption marker so you know the number is a lower bound, not a broken setup.

Session-scoped funnels and cookie-mode sites are unchanged.