By Brad Brooks and Brendan O’Brien VENICE, Fla. (Reuters) -Emergency crews raced on Thursday to reach stranded Florida residents as Hurricane Ian trained its sights on the Carolinas after cutting a coast-to-coast path of destruction across Florida, leaving behind deadly floodwaters, downed power lines and widespread damage. Ian, one of the strongest storms ever to hit the U.S. mainland, flooded Gulf Coast communities and knocked out power to millions before plowing across the peninsula to the Atlantic Ocean, where it regained strength ahead of another anticipated landfall in South Carolina on …