* feat(sessions): durable session state events with parent invalidation
Parents no longer act on stale child-session state: a durable, typed
signal log (session_state_events + per-agent heads) records direct human
messages to children, child spawn/terminal outcomes, goal changes, and
compaction at the seams where those facts are created. A frozen-watermark
cursor protocol (session_watch_cursors) delivers one coalesced system
notice to the parent through the existing system-event + heartbeat wake
idiom, acknowledged at the shared generic drain, with a deferred startup
sweep for restart recovery. session_status gains stateVersion and
changesSince (with exact pruned-history gap signaling); sessions_list
rows gain stateVersion.
Closes#104565
* chore: regenerate docs map and prompt snapshots for session_status changesSince
2bb79d10fd
