chore: drop the KubeVirt guest bits

The k3s-test workers never ran (they were stuck waiting for volume
binding) and will be re-added as microVMs, so remove their KubeVirt
configs and everything that only existed for KubeVirt guests:

- hosts/k8s/k3s-test-1-worker-{1,2,3} and their outputs
- lib/genKubeVirtGuestModule.nix and lib/genK3sAgentModule.nix (the
  latter was only used by the workers)
- the KubeVirt image upload recipes (upload-vm, upload-idols,
  upload-k3s-test) and the kubevirt image package in the idols outputs
- refresh the docs; keep only accurate historical mentions (e.g. the
  restic backup path must stay as it is)

vars/README.md

@@ -37,7 +37,7 @@ Comprehensive network configuration including:
 The networking configuration covers:
 
 - **Physical machines**: Desktop PCs, Apple Silicon systems, SBCs
-- **Virtual machines**: KubeVirt guests, K3s nodes
+- **Virtual machines**: VM guests, K3s nodes
 - **Kubernetes clusters**: Production and testing environments
 - **Network infrastructure**: Routers, gateways, and DNS configuration
 

vars/networking.nix

@@ -105,32 +105,32 @@ rec {
     # Kubernetes Clusters
     # ============================================
     k3s-test-1-master-1 = {
-      # KubeVirt VM
+      # VM
       iface = "enp2s0";
       ipv4 = "192.168.5.114";
     };
     k3s-test-1-master-2 = {
-      # KubeVirt VM
+      # VM
       iface = "enp2s0";
       ipv4 = "192.168.5.115";
     };
     k3s-test-1-master-3 = {
-      # KubeVirt VM
+      # VM
       iface = "enp2s0";
       ipv4 = "192.168.5.116";
     };
     k3s-test-1-worker-1 = {
-      # KubeVirt VM
+      # VM
       iface = "enp2s0";
       ipv4 = "192.168.5.111";
     };
     k3s-test-1-worker-2 = {
-      # KubeVirt VM
+      # VM
       iface = "enp2s0";
       ipv4 = "192.168.5.112";
     };
     k3s-test-1-worker-3 = {
-      # KubeVirt VM
+      # VM
       iface = "enp2s0";
       ipv4 = "192.168.5.113";
     };