fix(mgm): record disconnected state when sync stream setup fails

The connectToSyncStream failure path in handleSyncStream returned early
without updating syncStreamErr, so the client could still report healthy
even when stream setup failed. Mirror the receiveUpdatesEvents error path
by calling notifyDisconnected and setSyncStreamDisconnected.

shared/management/client/grpc.go

@@ -372,6 +372,8 @@ func (c *GrpcClient) handleSyncStream(ctx context.Context, serverPubKey wgtypes.
 	stream, err := c.connectToSyncStream(ctx, serverPubKey, sysInfo)
 	if err != nil {
 		log.Debugf("failed to open Management Service stream: %s", err)
+		c.notifyDisconnected(err)
+		c.setSyncStreamDisconnected(err)
 		if s, ok := gstatus.FromError(err); ok && s.Code() == codes.PermissionDenied {
 			return backoff.Permanent(err) // unrecoverable error, propagate to the upper layer
 		}