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/providers.tf

@@ -0,0 +1,27 @@
+terraform {
+  required_version = ">= 1.5"
+  required_providers {
+    kubernetes = {
+      source  = "hashicorp/kubernetes"
+      version = "~> 2.27"
+    }
+    helm = {
+      source  = "hashicorp/helm"
+      version = "~> 2.14"
+    }
+    null = {
+      source  = "hashicorp/null"
+      version = "~> 3.2"
+    }
+  }
+}
+
+provider "kubernetes" {
+  config_path = var.kubeconfig_path
+}
+
+provider "helm" {
+  kubernetes {
+    config_path = var.kubeconfig_path
+  }
+}