chore(coredns): keep Flux from pruning the Talos-owned Corefile

Step 1 of 2 to hand the coredns ConfigMap back to Talos. It is a Talos
bootstrap manifest (talos-bootstrap-manifests-inventory) that Flux also
applies; talosctl upgrade-k8s reverts Flux's Corefile. Bootstrap already
runs on Talos's Corefile (forward to the node resolver, which asks
k8s-gateway first), and k8s-gateway carries serve_stale for every name,
so the Flux copy is redundant.

With prune disabled, step 2 can drop the file without Flux deleting the
live ConfigMap.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

kubernetes/infrastructure/coredns-config/configmap.yaml

@@ -3,6 +3,10 @@ kind: ConfigMap
 metadata:
   name: coredns
   namespace: kube-system
+  # Talos owns this ConfigMap (bootstrap manifest). Flux must not delete it
+  # when this file is removed.
+  annotations:
+    kustomize.toolkit.fluxcd.io/prune: disabled
 data:
   Corefile: |
     # Delegate renner.uno to the in-cluster k8s_gateway resolver. It