refactor: simplify homelab bootstrap around static IPs and fresh runs

Make Terraform the source of truth for node IPs, remove guest-agent/SSH discovery from the normal workflow path, simplify the bootstrap controller to a fresh-run flow, and swap the initial CNI to Flannel so cluster readiness is easier to prove before reintroducing more complex reconcile behavior.

terraform/terraform.tfvars

@@ -17,3 +17,9 @@ control_plane_disk_size = "80G"
 worker_cores     = [4, 4, 4]
 worker_memory_mb = [12288, 12288, 12288]
 worker_disk_size = "120G"
+
+network_prefix_length = 10
+network_gateway       = "10.27.27.1"
+
+control_plane_ips = ["10.27.27.50", "10.27.27.51", "10.27.27.49"]
+worker_ips        = ["10.27.27.47", "10.27.27.46", "10.27.27.48"]