The WeCom adapter's _listen_loop() automatically reconnects when the
WebSocket drops, but it never called _mark_connected() after a successful
reconnection. This left the runtime status file (gateway_state.json) stuck
in "disconnected" even though the adapter was fully operational again.
Add self._mark_connected() right after _open_connection() succeeds so
that the dashboard and health probes report the correct state.
Tested by forcing a WebSocket close via the heartbeat loop and verifying
that the status file updated from "disconnected" back to "connected".
e77fd75c44