Ability to archive branches

That's not an issue but more a question and suggestion.

So it is related to Branches.

I can see there FILTERS: Active and Merged.

But all my branches are active. How can I move any branch to "Merged" state, so it will not appear in the list of active branches(1)?

Also, I have some branches, that are dead ends. They are definitely not active, so I dont want to see them in the list. Neither they are "Merged". I also don't want to delete such branches. They still contain useful code that I can use in future. SO I would like to have the third filter there, called "Archive" or like that(2).

And I believe some context help will be appreciated near by those filters(3), so anyone can clearly know how to move some branch to any category.