- ca_timeout_cb: removed etcp_connection_close, ETCP lives past 3s timeout
- ca_state.cancelled flag + chat_core_connect_auto_cancel() for external cancel
- chat_core_connect_auto returns ca_state* via out_state
- Rewritten auto_connect: cursor (ch,peer) instead of bulk collect
- GC every 1s: closes flights with no link_status after 3s
- ac_result_cb no longer clears ca_state (GC handles cleanup)
- stop: cancels all flights via chat_core_connect_auto_cancel