notifyAppResumed method
Reconciles the connection after the app returns to the foreground.
Called automatically when RealtimeConfig.lifecycleAware is on and a Flutter binding exists. Call it yourself where it does not — a pure Dart entrypoint, a background isolate, or an app that already owns its own lifecycle observer and would rather drive this explicitly.
It does two things: it retires a state that says connected while the transport knows the socket is gone (the usual result of an iOS background), and it runs a pending reconnect whose timer the OS suspended. Both would otherwise resolve only after the server timeout elapses.
It cannot detect a socket that died silently and that the transport still
believes is open: nothing has arrived to say otherwise, and the SignalR hub
protocol offers no client-initiated liveness check. That case still belongs
to HeartbeatConfig and the server timeout.
Implementation
@override
void notifyAppResumed() => appResumedCount++;