feat(terraform): enable S3 remote state backend (MinIO)

Migrate terraform state from local file to MinIO S3 bucket (terraform-state).
Backend config: https://minio-api.riotpiao.homelab.com (external endpoint).
State now persisted remotely, shared across team, safe for cluster rebuild.

Also added terraform-state bucket to MinIO managed buckets.

terraform/minio.tf

@@ -66,6 +66,7 @@ resource "helm_release" "minio" {
 
       # Buckets auto-created on install (all-in-one, no post-hook needed)
       buckets = [
+        { name = "terraform-state", policy = "none", purge = false },
         { name = "vault", policy = "none", purge = false },
         { name = "riotpiao-models", policy = "none", purge = false },
         { name = "loki-chunks", policy = "none", purge = false },