When the Codex OAuth token endpoint returns 429 (usage-limit / quota
exhaustion), refresh_codex_oauth_pure raised a generic auth error that the
gateway surfaced as 'Primary provider auth failed: No Codex credentials
stored. Run hermes auth', prompting re-auth that cannot lift a quota cap.
Classify 429 distinctly (codex_rate_limited, relogin_required=False) with a
non-alarming quota message that honors Retry-After, log it as
'Primary provider rate-limited (429)', and stop format_auth_error from
appending the re-authenticate remediation. Also log the fallback provider's
literal config key instead of the resolved runtime category.
Refs #32790
f1422ffd77