Photo: Michael Nigro/Sipa/AP As the curtain goes up on the post–Labor Day push to Election Day, Mayor Adams, tanking in the polls , is making unsubtle tribal appeals to the Black communities that powered him to victory four years ago, frequently reminding voters that he is second Black mayor in city history after David Dinkins. But political leaders in vote-rich Harlem, Central Brooklyn, and Southeast Queens neighborhoods are increasingly connecting with Zohran Mamdani or Andrew Cuomo, and