KIM HARRISBERG  SOUTH Africa's northern Limpopo province is known for its lush forests, national parks, fruit farms and heritage sites - but lately, its green image has come under threat from a proposed multi-billion-dollar industrial mega-project. Made up of a cluster of 20 steel and other metalworking plants and fuelled by a coal-fired power station, supporters say the project would create much-needed local jobs, while opponents warn it would spell catastrophe for the climate and health. "We are worried that if the project goes ahead, we will be wearing masks for years to come, not because of coronavirus but because…