SYDNEY — Australian authorities are responding to a surge in antisemitic and Islamophobic hate crimes. Australian police said offensive graffiti that demeaned Islam was found under a bridge in the Sydney suburb of Sefton on Sunday. The New South Wales state Premier Chris Minns said “this racism and Islamophobia is disgusting and corrosive to the very fabric” of multiculturalism. Sefton is a majority-Muslim district. …