Whether an access token is currently held.
Register a new account (server may have registration disabled).
Sign in with the OAuth2 password grant and store the tokens.
Forget the stored tokens.
Last-write-wins upsert of rows into table. Returns rows written.
Fetch rows from table, optionally only those changed after since.
Optionalsince: stringHard-delete one extension-repo row for the signed-in user.
Account and library sync against the Nyora sync server.