Read up to 20 presentations in one request

The batch form of the GET. Send {"urls": [...]}, {"items": [{"url"} | {"handle","slug"}, ...]}, or a bare JSON array of watch URLs; each item resolves on its own, so one bad address fails its row and not the batch. Every item costs one slot of the same per-IP window as a GET (60 per 10 minutes anonymous, 300 with a credential); items past the window come back as CONTEXT_RATE_LIMITED rows rather than failing the request.