Get NBA player tracking stats for a season

NBA-only route. Returns the single (player, season) document from the derived player_tracking_stats collection — the leaguedashptstats per-game aggregate combining four slices: drives, touches (possessions), pull_up, and catch_shoot, plus games played and minutes per game. A slice the player had no rows in comes back null (e.g. a center who never takes pull-up jumpers). Players with no tracking doc for the season return 404 data_not_yet_available.