getToken method
Return the full Basic <base64> header instead of stripping the prefix.
The realtime WS handshake sends {type: auth, token: <getToken()>}; the
server-side handler (e.g. CHT user_client_ws_handler:handle_auth/2)
inspects the token's prefix to choose the auth scheme. Without the
Basic prefix the token would be misclassified as a bearer JWT,
fail JWT decoding, and the connection would close with auth_error: invalid_token.
Bearer auth keeps the base behaviour (strip and ship the JWT bare) —
see AuthInterceptor.getToken in auth_interceptor.dart.
Implementation
@override
Future<String> getToken() async => getAuthHeader();