Mayor Mamdani can look out from his window at City Hall to see the homeless crisis firsthand.
A 52-year-old homeless man was bedding down on the frozen sidewalk across the street from the City Hall guardhouse in Lower Manhattan Thursday — just one of thousands braving a killer cold spell on the streets as the lefty mayor takes a hands-off approach to the crisis.
The Post called 311 to get the man some help — but no one came…