Agent inbounds defined centrally store an empty originNodeGuid, and
inbounds re-homed from a panel node keep the previous host's GUID, so
the inbounds page looked the agent's online set up under a key it is
never filed under. GetInboundsSlim now annotates agent-hosted
inbounds at read time with the node's effective attribution key
(the key SetAgentOnlineClients files onlines under).
