Worked example and make target for the kvm-ssh Secret

docs/kvm-provider.md walks through key generation, ssh-copy-id,
ssh-keyscan under the address the operator dials, and the Secret from
the private key plus ~/.ssh/kvm_known_hosts. make kvm-ssh-secret runs
the same as an apply with KVM_SSH_KEY / KVM_KNOWN_HOSTS overrides and
refuses a .pub, the classic mistake. README mirrors the short form.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

Makefile

@@ -178,6 +178,20 @@ uninstall: manifests kustomize ## Uninstall CRDs from the K8s cluster specified
 	@out="$$( "$(KUSTOMIZE)" build config/crd 2>/dev/null || true )"; \
 	if [ -n "$$out" ]; then echo "$$out" | "$(KUBECTL)" delete --ignore-not-found=$(ignore-not-found) -f -; else echo "No CRDs to delete; skipping."; fi
 
+KVM_SSH_KEY ?= $(HOME)/.ssh/proxy-operator_ed25519
+KVM_KNOWN_HOSTS ?= $(HOME)/.ssh/kvm_known_hosts
+KVM_SSH_NAMESPACE ?= egress-proxies-operator-system
+
+.PHONY: kvm-ssh-secret
+kvm-ssh-secret: ## Create or update the kvm-ssh Secret from KVM_SSH_KEY (private key) and KVM_KNOWN_HOSTS.
+	@test -f "$(KVM_SSH_KEY)" || { echo "KVM_SSH_KEY=$(KVM_SSH_KEY) not found"; exit 1; }
+	@test -f "$(KVM_KNOWN_HOSTS)" || { echo "KVM_KNOWN_HOSTS=$(KVM_KNOWN_HOSTS) not found"; exit 1; }
+	@grep -q 'PRIVATE KEY' "$(KVM_SSH_KEY)" || { echo "KVM_SSH_KEY=$(KVM_SSH_KEY) is not a private key (did you pass the .pub?)"; exit 1; }
+	"$(KUBECTL)" -n $(KVM_SSH_NAMESPACE) create secret generic kvm-ssh \
+		--from-file=id_ed25519="$(KVM_SSH_KEY)" \
+		--from-file=known_hosts="$(KVM_KNOWN_HOSTS)" \
+		--dry-run=client -o yaml | "$(KUBECTL)" apply -f -
+
 .PHONY: deploy
 deploy: manifests kustomize ## Deploy controller to the K8s cluster specified in ~/.kube/config.
 	cd config/manager && "$(KUSTOMIZE)" edit set image controller=${IMG}