Owner Entry

C4 drill-in: ONE library entry in full. Lookup by id (the sha16 categories key — sha1(question.strip().lower())[:16] — OR a raw store key: a reduce-cache "ns|depth|question" key or a yield-record id) or by question (exact text, normalized). Returns {question, kind, vertical, activity, topic, ts, payload} where payload is the stored reduction tree | decide frame | yield record, VERBATIM. 404 when nothing matches.