Next 16 cache canary

Refresh repeatedly. If 'use cache' works, renderedAt and randomTrace stay the same until the cache expires or a Server Action calls revalidateTag('homepage').

{
  "renderedAt": "2026-05-26T18:57:56.592Z",
  "randomTrace": "fc86b73c-9582-451b-b593-92034eaa74e4"
}