Mayor Zohran Mamdani took advantage of his taxpayer-funded housing to film a slick campaign video for a lefty candidate in a contentious New York congressional race — sparking backlash from critics who said it could run afoul of conflict of interest laws. Hizzoner, in the social media clip released Thursday, could be seen palling around with Parkland survivor David Hogg at Gracie Mansion. The mayor and Hogg, of the group, Leaders We Deserve, solicitated donations for Democratic Socialists of America member Claire Valdez, who is running for New York’s 7th House District seat. Mayor Mamdani filmed a slick campaign video for a lefty candidate and Democratic Socialists of America member Claire Valdez at Gracie Mansion. Instagram/claireforny Councilman Phil Wong’s office told The Post the lawmaker was planning to file a complaint with the city’s Conflict of Interest Board over the video. One Democratic operative called it “unseemly,” but said they weren’t sure if it actually crossed a legal line.…