This Manhattan dome can finally become someone’s home. A striking penthouse crowned by a 40-foot golden dome is heading to auction with an opening bid that could represent a staggering 76% discount off its initial asking price , The Post has learned. The trophy residence atop the landmarked Sohmer Piano Building in the Flatiron District, listed in late 2024 for $25 million, will go under the hammer July 29 at Sotheby’s New York through Concierge Auctions.  Bids are expected to start between $6