A Secret volume is owned by root and the sidecar runs as 65532, so defaultMode 0400
left it unable to open /var/run/llm-key/key: the container restarted with
'permission denied' on every start and never minted a token.
Set mode 0440 and give the pod fsGroup 65532, so the group that owns the volume can
read the key while nothing else on the host can.