Instead of creating a long-lived Vault token in Terraform (which gets
invalidated when Terraform recreates it), monitoring01 now uses its
existing AppRole credentials to fetch a fresh token for Prometheus.
Changes:
- Add prometheus-metrics policy to monitoring01's AppRole
- Remove vault_token.prometheus_metrics resource from Terraform
- Remove openbao-token KV secret from Terraform
- Add systemd service to fetch AppRole token on boot
- Add systemd timer to refresh token every 30 minutes
This ensures Prometheus always has a valid token without depending on
Terraform state or manual intervention.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>