feat: Add HA Kubernetes cluster with Terraform + Ansible

- 3x CX23 control plane nodes (HA)
- 4x CX33 worker nodes
- k3s with embedded etcd
- Hetzner CCM for load balancers
- Gitea CI/CD workflows
- Backblaze B2 for Terraform state

terraform/backend.tf

@@ -0,0 +1,10 @@
+terraform {
+  backend "s3" {
+    key                         = "terraform.tfstate"
+    region                      = "auto"
+    skip_credentials_validation = true
+    skip_metadata_api_check     = true
+    skip_region_validation      = true
+    force_path_style            = true
+  }
+}