As New York braced for a week in the global spotlight, violence erupted at the heart of the city’s transit network: six people were wounded in a stabbing at Penn Station, Mayor Zohran Mamdani said, just as the metropolitan area prepared to host the NBA Finals and football’s World Cup. Authorities detained a suspect after the attack, and all six victims were taken to a hospital, according to the New York Fire Department. One person suffered serious injuries. Fire officials had first said five people were hurt, but Mamdani…