Allow managers to keep track of progress in monthly active teens

ik it doesn't rly fit the theme to build new features into the team page just for premium perks but right now there's no way for ppl to tell what an active teen is and who needs to sign and whatever.

allowing org managers to see team member last active dates might help.

or just completely building a new tab for premium perks and including something there to help with this.

Start by reviewing the existing team page and how monthly active teens, manager permissions, signatures, and premium perks are represented. Clarify whether progress belongs on the team page or in a new premium-perks tab, then define the information managers must see and how completion will be verified.

Written by the indexing model from the issue text.