Modified bundleWarmAssetsForCycle to return the deduplicated match IDs
of warm-set replays, and added a call to promoteRecentReplays in the
build cycle. This implements plan §8.2.5: index builder promotes recent
replays from B2 cold archive to R2 warm cache.
Acceptance criteria for plan-gap bead bf-jfmo:
- /r2/replays/{id}.json.gz will return valid gzipped replay JSON once
the Cloudflare Pages R2 bucket binding (ACB_BUCKET) is configured
- R2 bucket exists with replay objects after each build cycle
- Index builder has R2 S3 client configured (credentials via env vars)
Closes: bf-jfmo
3bd6ed45f9