Codex records with their ten join columns (passages, measures, instruments, …)

The join layer over the codex: for each reachable record, the arrays that connect it to passages, actions, stories, measures, instruments, signals, goals, situations and presentations. Management-HR records only on this public surface — records in other domains are WITHHELD, and a lookup for one answers 404 record_withheld naming its domain, so absence is never silent. ?codex_id or ?slug returns a single record; no parameter returns the bulk feed plus per-lens coverage counts, because the join columns are unevenly populated and a caller should be able to see that rather than infer it.