TPG.SetupTeams

Register TPG.Teams with the engine's team library. Safety net: never clobber a team another addon already registered (e.g. ULX UTeam role-teams). This only ever overwrites an ID it set up itself; if team.Valid(id) is already true and TPG._ownTeams[id] is not set, that means something else holds this ID, so it skips that entry and warns instead of stomping it. That check only bites on the FIRST call for a given ID: once TPG has registered a team, TPG._ownTeams[id] stays true, so a later call (e.g. a hot reload) re-runs team.SetUp for it unconditionally rather than tripping the "already in use" branch again. Runs once automatically at the bottom of this file; safe to call again if teams ever need rebuilding.