- Add etcp_add_conn_status_cbk/remove/set — unified callback for all connections
- 4 statuses: NEW, UP, DOWN, DELETE — one subscription covers all connections
- Fire points in etcp.c: create→NEW, on_up→UP, on_down→DOWN, close→DELETE
- chat_sync.c: replace cs_on_new_conn+per-conn subs with cs_on_conn_status
- db_sync.c: same migration to instance-level callback
- cs_is_peer_online: use conn->links_up instead of link->link_status (was 0 during INIT handshake)
Evgeny
aa1ed006d5