v1.0.3
feat: add tcgplayer card listings endpoint (v1.0.3) Add CardListingsResource.tcgplayer / iterate_tcgplayer / all_tcgplayer (sync + async) backed by GET /v1/cards/:id/listings/tcgplayer, with a TcgplayerListing model. Params mirror cardmarket except variant -> printing. Bump version to 1.0.3.