Decide and implement: either treat the non-terminating Bun socket as the product bug it appears to be, or gate the suite

From dispatch finding (task `cron-kriszyp-27ecd1-2026081706`):

- F-292 — Still live and it is the single thing blocking the pipeline's only APPROVED PR: under Bun, a streaming `iterable-rest` response delivers its complete body but **never closes the socket**, including on the clean-completion control arm, so #2070's own promoted spec times out at 15s on CI Bun shard 4/6 while being 29/29 green locally on Node.

Start with the promoted spec from #2070 and reproduce its streaming iterable-rest response on Bun CI shard 4/6, comparing it with the Node result. Determine whether the non-closing socket is a product bug or whether the suite should be gated; done means the selected path is implemented and the pipeline is no longer blocked by the 15-second timeout.

Written by the indexing model from the issue text.