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]>

terraform/main.tf

@@ -0,0 +1,8 @@
+locals {
+  kubeconfig_path = var.kubeconfig_path
+  cluster_domain  = var.cluster_domain
+}
+
+# Helm repositories will be created in helm-repositories.tf
+# Namespaces will be created in bootstrap/namespaces.tf
+# Helm releases will be created in helm-releases/*.tf