After opening the season with nine straight losses, the 49ers have won three of their past four games. A sign that success has produced some swagger: They are now practicing touchdown celebrations. Yes, the 49ers plan to finally take advantage of the NFL’s offseason decision to allow players to have more fun in the end zone when they host the Titans on Sunday. Before practice Wednesday, tight end Garrett Celek said the team’s initial TD-celebration work was planned for later in the day. “We’ve been talking about it as an offense a little bit,” tight end Garrett Celek said.