requireTeam() now respects an optional ?teams= query param from Admin
users as a voluntary scope filter. When the Admin Scope Toggle is set
to 'My Teams', the frontend sends ?teams=STEAM,ACCESS-ENG and the
backend applies the filter. When set to 'All BUs' (no param), Admin
gets the full unfiltered view.
Non-admin users continue to be enforced by their bu_teams assignment
regardless of any query param.