List Related Bills

Companion, prior-session and superseded-bill cross-references.

These have been collected all along (~100k rows, of which ~47k are prior-session) and were never exposed -- the single most-requested thing for multi-year policy tracking, because a bill that dies and returns next session under a new number is otherwise untrackable.

Upstream gives us only the related bill's IDENTIFIER, so the target is resolved here, scoped to the same jurisdiction. Same-session companions usually resolve; prior-session links usually do not, because that session is outside this corpus. Unresolved links still return their identifier rather than being dropped.