Brings in main 6741f4f165 through part 1. Main's history page now reads with a
HistoryReader, so the published current work moves to agent-session-published-work.ts and
lays over each finished page. Main's new Stop path (chat-stop target, acceptance, unconfirmed
note, targeted cancel) and the per-subagent row writer read what runs through the host's
current-work projection, as the rest of this part does.