PARADISE, Calif. — Laura Nelson was dreading this drive. It’s bad enough seeing the mailboxes for houses that no longer exist, the dusty roads lined with the blackened skeletons of trees. But the day is also bone-dry and scorching, the smoke from a distant fire casting a too-familiar pallor over the landscape. Her car bumps over rough patches of pavement — places where the asphalt was melted by vehicles engulfed in flames.