By Joice Alves and Josephine Mason LONDON (Reuters) – Plans by European companies to hike wages and pay one-off bonuses to help staff cope with a torrid winter are raising alarm among investors concerned that the extra cost could hurt profits and undermine the region’s economy. Stellantis and LVMH are among a slew of companies offering one-off bonuses to most employees to help with surging food and energy bills over the winter. While those payouts are relatively easy for big multinational companies to digest, a bigger worry is that many are also bringing forward negotiations for annual pay rev…