Save groups, profile, visibility, summary, display name, and cumulative
stats to a new mesh.peer_state table on disconnect. On reconnect (same
meshId + memberId), restore them automatically — hello groups take
precedence over stored groups if provided. Broadcast peer_returned
system event with last-seen time and summary to other peers.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
