fix: use self-contained Terraform variable validations

Terraform variable validation blocks can only reference the variable under validation. Replace count-based checks with fixed-length validations for the current 3 control planes and 3 workers.

terraform/variables.tf

@@ -105,8 +105,8 @@ variable "control_plane_ips" {
   description = "Static IPv4 addresses for control plane VMs"
 
   validation {
-    condition     = length(var.control_plane_ips) == var.control_plane_count
-    error_message = "control_plane_ips length must match control_plane_count."
+    condition     = length(var.control_plane_ips) == 3
+    error_message = "control_plane_ips must contain exactly 3 IPs."
   }
 }
 
@@ -116,8 +116,8 @@ variable "worker_ips" {
   description = "Static IPv4 addresses for worker VMs"
 
   validation {
-    condition     = length(var.worker_ips) == var.worker_count
-    error_message = "worker_ips length must match worker_count."
+    condition     = length(var.worker_ips) == 3
+    error_message = "worker_ips must contain exactly 3 IPs."
   }
 }