Adds k8s/traefik-config.yaml to enable JSON-format access logs on
the K3s built-in Traefik for diagnosing whether subv webhooks from
volcengine are dropped between ingress and Django, or simply not
sent. Drops Authorization/Cookie headers to avoid leaking secrets.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
