Terraform modules I reuse on every new infra project

Draft notes, not published yet.

• VM lifecycle module (auto-suspend on idle, the same pattern behind the 40% cost cut on the cost audit service)
• GKE cluster baseline (network policy, node pools, workload identity wired up by default)
• Observability stack module (Prometheus + Grafana, provisioned the same way every time instead of clicked together by hand)

Full write-up coming once the modules themselves are cleaned up enough to link to directly.