mapper: include UserProfiles in policy-change MapResponses

hscontrol/mapper/mapper.go

@@ -239,7 +239,10 @@ func (m *mapper) policyChangeResponse(
 
 	// Send remaining peers in PeersChanged - their AllowedIPs may have
 	// changed due to the policy update (e.g., different routes allowed).
+	// Cross-user peers must also carry their user profile, otherwise the
+	// client's netmap shows the peer without a UserProfiles[user] entry.
 	if currentPeers.Len() > 0 {
+		builder.WithUserProfiles(currentPeers)
 		builder.WithPeerChanges(currentPeers)
 	}