The session.list projection dropped the durable lineage root returned by
SessionDB, so RPC consumers could not group a compressed conversation
with its continuation — REST (/api/sessions) already projected it, and
the desktop store keys pinning and lineage dedup on the field
(apps/desktop/src/store/session.ts::sessionPinId).
Forward `_lineage_root_id` through `_session_row_summary`, declare it on
the `SessionListRow` wire contract, and regenerate the TS/OpenRPC
artifacts so every consumer sees it.
Fixes#66663
Salvaged from #66675 by @Sanjays2402 (authorship preserved); adapted to
methods_session.py and extended with the wire contract + regenerated
artifacts.
1212a7f18c