Beirut — Lebanon’s parliament voted Thursday to elect the country’s army commander, Joseph Aoun, as head of state, filling a more than two-year-long presidential vacuum. The vote came weeks after a tenuous ceasefire agreement halted a 14-month conflict between Israel and the Lebanese militant group Hezbollah and at a time when Lebanon’s leaders are seeking international assistance for reconstruction. Aoun, no relation to former president Michel Aoun, was widely seen as the preferred candidate of the United States and Saudi Arabia, whose assistance Lebanon will need as it seeks to rebuild. The session was the legislature’s 13th attempt to elect