No person shall be eligible to hold elective office under the mayor-council plan unless the person is a registered voter of the city at the time of filing his or her declaration of candidacy and has been a resident of the city for a period of at least one year next preceding his or her election. Residence and voting within the limits of any territory which has been included in, annexed to, or consolidated with such city is construed to have been residence within the city. A mayor or councilmember shall hold within the city government no other public office or employment except as permitted under the provisions of chapter
42.23 RCW.