* fix(auth): preserve 401 status for expired JWTs in OTel traces
Expired JWT access tokens raised a generic Exception with no status
code attached. Because the codeless exception was logged to OTel via
post_call_failure_hook before auth_exception_handler re-wrapped it as
ProxyException(401), the OTel span never set http.response.status_code
and trace viewers displayed it as a generic 500. Clients still got a
401 back, so traces and actual responses diverged.
Raise ProxyException(code=401, type=expired_key) directly at the source
in both JWT decode paths so the 401 is consistent across the client
response and the OTel http.response.status_code attribute, matching how
virtual-key expirations are handled.
* fix(auth): preserve 401 for expired JWTs on issuer-scoped path
The issuer-scoped JWT path (_auth_jwt_with_issuer) still raised a generic
Exception on expiry, surfacing as a 500 in client responses and OTel traces.
Raise ProxyException with expired_key/401 there too, matching auth_jwt, and
add a regression test exercising the issuer path end-to-end