Make it optional to have the branch filter enabled by default.

We have a large repository, and I find myself always turning on the branch filter. It would be great to be able to have that filter enable for evey new worktree. 

(It's the blue icon next to the branch name)

<img width="135" height="66" alt="Image" src="https://github.com/user-attachments/assets/59f08cb6-2c34-49b9-a5c8-c7b86a0cda10" />