The leader of Portland's powerful public schools foundation said Tuesday he'll leave his post at the end of June. Dan Ryan had led All Hands Raised, which supports Portland's public schools, after serving on the city's board of education. A note announcing his resignation gave no reason for his decision. Ryan will leave his post June 30, remaining on board "while the Board of Directors identifies a new leader and ensures a smooth and seamless transition," Board Chair Trever Cartwright wrote. “I…