ST. PAUL, Minn. — The usual excitement of a new session of the Legislature had a solemn note: A memorial to House Speaker Melissa Hortman and her husband, who were assassinated at their suburban home in June. Hortman’s seat in the chamber was ceremoniously vacant. On the desk: A fresh bouquet, a portrait and a gavel. Governor Tim Walz spoke: “Since I have had the privilege of serving in state government, this is the first time without Melissa the Speaker.”