Public Teams Catalog

Public endpoint: full catalog of team types with display data.

Replaces the hard-coded frontend/src/lib/team-catalog.ts. Returns the full payload (composition + display metadata + use_cases + faqs + how_it_works) so the /teams page and /teams/[slug] page can render entirely from this one response.

Honors the teams_enabled env kill-switch — if off, returns an empty list (matching the behavior of /public/team-state-overrides which forces HIDDEN on every row).

Returns only live/beta/coming_soon teams. draft and hidden stay server-side to avoid existence leaks and match the public filter the frontend already applies.