Reverts the plugins/dashboard_auth half of ca38caeea0.
_request_limited_response streamed the body via iter_bytes() (already
gzip-decoded by httpx) and rebuilt an httpx.Response with the ORIGINAL
headers, Content-Encoding: gzip included, so .json() tried to gunzip
plaintext. Every Nous Portal dashboard login failed with
503 "Provider unreachable: Portal token endpoint unreachable: Error -3
while decompressing data: incorrect header check". Self-hosted OIDC
discovery/token/revocation used the same helper.
The urllib half (gateway health probe, ElevenLabs voices) is kept:
urllib does not decode Content-Encoding, and c061068b26 builds on its
_read_dashboard_json_response helper.
8a33891bdd