The Wellesley School Committee voted Tuesday night to offer David Lussier, its pick for the district’s new superintendent, a three-year contract with a first-year salary of $185,000. The committee voted unanimously on May 8 to select Lussier, currently the executive director for educator quality in the Austin Independent School District in Texas, to step into the role being vacated by Superintendent Bella Wong at the end of this school year. Lussier said in an e-mail that his base salary in Texas is $110,000 this year. Wong’s salary this year is $178,073, according to the superintendent’s office. After the first year of the contract, the town will have to vote on Lussier’s salary as part of its annual budget, said School Committee member K.C. Kato.