The German shipyard Lürssen—which will deliver the world’s largest privately owned yacht, the 591-foot Azzam, this fall—continues to impress with its newest build. Developed under the project name Niki, the six-deck yacht recently completed sea trials, and its owner is set to christen the vessel Solandge upon delivery this fall. The 280-foot yacht features exterior lines penned by the Norwegian naval architect (and frequent Lürssen collaborator) Espen Oeino, with interiors from interior designer Aileen Rodrigu…