authenticate
Exchanges one of your own tokens for an SDK session, unlocking the content APIs.
Call it after the user has signed in on your side. On success state becomes AuthState.Identified.User; on failure it is left as it was and the error says why — a rejected token is CgsError.Auth.Unauthorized, an unreachable server is a CgsError.Network, and only the latter is worth retrying.
The resulting session is persisted and refreshed automatically, so this belongs in your sign-in flow, not in Application.onCreate.
Return
CgsResult.Success once the session is open, CgsResult.Failure otherwise.
Parameters
hostToken
the token your backend issues for the signed-in user.