v2.0a5

Fixed

• Soliplex web login works against fragment-based auth callbacks
  (#3476). Soliplex soliplex#1415 moved the post-IdP return_to
  tokens from the query string into the URL fragment; the feature's
  popup poller read only Uri.queryParameters, so every web login
  against such a backend failed with "No token in auth callback" (the
  href.contains('token=') poll trigger still fired, but the params
  were behind the #). extractCallbackParams now reads the
  fragment's ?-part after the query string — the same precedence as
  the Soliplex web client's callback_params_parser — so older
  query-string backends keep working. Native (flutter_appauth)
  login is unaffected.