Bare -r/--resume now opens a numbered picker merging jsonl (source of
truth) with the xiaohe hosted-session index, deduped by cli_session_id
and sorted by real content activity (not jsonl mtime, which the xiaohe
projection re-touches). -l gains a Src column (xiaohe/cli); -r <id> and
-c stay passthrough. Adds read-only xiaohe_sessions data layer + tests.
