feat: Terraform foundation for cluster & app bootstrap

Phase 1 infrastructure-as-code setup:
- Core providers (kubernetes, helm, null)
- 15 Helm repositories (grafana, minio, prometheus, etc.)
- Namespace scaffolding (15 namespaces with pod-security labels)
- Storage classes (longhorn, longhorn-kafka with prevent_destroy)
- TLS certificate bootstrap (selfsigned, CA, wildcard cert)
- Remote state backend config (local for now, S3/GCS TODO)
- Variable definitions for all secrets/OIDC clients

Tested: terraform plan passes with no changes (bootstrap infrastructure ready)
Next: Create 25 helm_release resources (Phase 2-4)

Kept helmfile intact; network/Cilium managed via helmfile (no config risk)
Co-Authored-By: Claude Haiku 4.5 <[email protected]>

.gitignore

@@ -37,4 +37,5 @@ k8s/storage/test/test
 # Allowed markdown: CLAUDE.example.md, README.md, TROUBLESHOOTING.md
 CLAUDE.md
 
-skills-lock.json
+skills-lock.jsonterraform/.terraform/
+terraform/*.tfstate*