With one foot out the door, Mayor Bill de Blasio is setting up a nightmare budget crunch for Gotham’s next mayor — and trying to hide the damage in the process. De Blasio’s latest financial plan, which went into effect July 1, projects a $4.1 billion cash shortfall next year — a huge chunk of change (even by New York standards) the next mayor must grapple with the moment he takes office Jan. 1. Yet the gap is actually $700 million higher, totaling $4.8 billion. On Tuesday, Citizens Budget Commission head Andrew Rein pegged the deficit at $5.4 billion, including...