In CheckIfMyAnimeListLoggedIn and MyAnimeListLogin the keyring lookups
assigned MyAnimeListAccessToken to refreshToken and
MyAnimeListRefreshToken to accessToken. Downstream code checks
len(accessToken.Data) for login state and assigns
accessToken.Data -> myAnimeListJwt.AccessToken, so the swap gated
login on the refresh token and stored each token in the wrong field.
Swap the variable names to match their keyring keys so login detection,
JWT restoration, and the empty-token fallback in MyAnimeListLogin use
the correct values.
