sessionRefreshFlow
Hot stream of srcNodeNum values, emitted exactly once per call to recordSession with a non-empty passkey. Used by EnsureRemoteAdminSessionUseCase to await a session refresh from a specific node without polling.
Backed by a MutableSharedFlow with no replay; subscribers must subscribe before dispatching the request that triggers the refresh. Exposed as a Flow via kotlinx.coroutines.flow.SharedFlow.asFlow (kotlinx.coroutines 1.11+) to hide the SharedFlow API from consumers while preserving hot-stream semantics.