void setCached() leaves the R2 put unregistered, and workerd cancels
unregistered pending I/O once the response is sent — the write never
lands, so the caches behind domain overview, domain keyword/page pages,
and SERP research are silently re-fetched (and re-charged) on every
call. Register the writes with waitUntil, matching the pattern already
used in instrumentation.ts and brandLookup.ts.
