refactor: remove per-SA infrastructure and feature gates

Delete authentication and authorization packages, feature gates,
k8smaintainer tool, SA demo scripts, and documentation. Remove
k8s.io/kubernetes dependency and unnecessary k8s staging replace
directives.

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

Author: pedjak

Makefile

@@ -160,10 +160,6 @@ lint-custom: custom-linter-build #EXHELP Call custom linter for the project
 lint-api-diff: $(GOLANGCI_LINT) #HELP Validate API changes using kube-api-linter with diff-aware analysis
 	hack/api-lint-diff/run.sh
 
-.PHONY: k8s-pin
-k8s-pin: #EXHELP Pin k8s staging modules based on k8s.io/kubernetes version (in go.mod or from K8S_IO_K8S_VERSION env var) and run go mod tidy.
-	K8S_IO_K8S_VERSION='$(K8S_IO_K8S_VERSION)' go run hack/tools/k8smaintainer/main.go
-
 .PHONY: tidy #HELP Run go mod tidy.
 tidy:
 	go mod tidy
@@ -225,7 +221,7 @@ generate: $(CONTROLLER_GEN) generate-mocks #EXHELP Generate code containing Deep
 	done
 
 .PHONY: verify
-verify: k8s-pin kind-verify-versions fmt generate manifests update-tls-profiles crd-ref-docs update-registryv1-bundle-schema verify-bingo #HELP Verify all generated code is up-to-date. Runs k8s-pin instead of just tidy.
+verify: tidy kind-verify-versions fmt generate manifests update-tls-profiles crd-ref-docs update-registryv1-bundle-schema verify-bingo #HELP Verify all generated code is up-to-date.
 	git diff --exit-code
 
 .PHONY: verify-bingo

docs/draft/howto/use-synthetic-permissions.md

@@ -33,7 +33,6 @@ require (
 	go.podman.io/image/v5 v5.40.0
 	go.uber.org/mock v0.6.0
 	golang.org/x/exp v0.0.0-20260410095643-746e56fc9e2f
-	golang.org/x/mod v0.37.0
 	golang.org/x/sync v0.21.0
 	golang.org/x/tools v0.46.0
 	helm.sh/helm/v3 v3.21.1
@@ -45,7 +44,6 @@ require (
 	k8s.io/client-go v1.5.2
 	k8s.io/component-base v0.36.1
 	k8s.io/klog/v2 v2.140.0
-	k8s.io/kubernetes v1.36.1
 	k8s.io/utils v0.0.0-20260319190234-28399d86e0b5
 	pkg.package-operator.run/boxcutter v0.14.0
 	sigs.k8s.io/controller-runtime v0.24.1
@@ -55,10 +53,7 @@ require (
 	sigs.k8s.io/yaml v1.6.0
 )
 
-require (
-	k8s.io/component-helpers v0.36.1 // indirect
-	k8s.io/kube-openapi v0.0.0-20260520065146-aa012df4f4af // indirect
-)
+require k8s.io/kube-openapi v0.0.0-20260520065146-aa012df4f4af // indirect
 
 require (
 	cel.dev/expr v0.25.2 // indirect
@@ -227,6 +222,7 @@ require (
 	go.yaml.in/yaml/v2 v2.4.4 // indirect
 	go.yaml.in/yaml/v3 v3.0.4 // indirect
 	golang.org/x/crypto v0.53.0 // indirect
+	golang.org/x/mod v0.37.0 // indirect
 	golang.org/x/net v0.56.0 // indirect
 	golang.org/x/oauth2 v0.36.0 // indirect
 	golang.org/x/sys v0.46.0 // indirect
@@ -244,7 +240,6 @@ require (
 	gopkg.in/warnings.v0 v0.1.2 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
-	k8s.io/controller-manager v0.33.2 // indirect
 	k8s.io/kubectl v0.36.1 // indirect
 	k8s.io/streaming v0.36.1 // indirect
 	oras.land/oras-go/v2 v2.6.1 // indirect
@@ -270,54 +265,12 @@ replace k8s.io/cli-runtime => k8s.io/cli-runtime v0.36.1
 
 replace k8s.io/client-go => k8s.io/client-go v0.36.1
 
-replace k8s.io/cloud-provider => k8s.io/cloud-provider v0.36.1
-
-replace k8s.io/cluster-bootstrap => k8s.io/cluster-bootstrap v0.36.1
-
-replace k8s.io/code-generator => k8s.io/code-generator v0.36.1
-
 replace k8s.io/component-base => k8s.io/component-base v0.36.1
 
 replace k8s.io/component-helpers => k8s.io/component-helpers v0.36.1
 
 replace k8s.io/controller-manager => k8s.io/controller-manager v0.36.1
 
-replace k8s.io/cri-api => k8s.io/cri-api v0.36.1
-
-replace k8s.io/cri-client => k8s.io/cri-client v0.36.1
-
-replace k8s.io/cri-streaming => k8s.io/cri-streaming v0.36.1
-
-replace k8s.io/csi-translation-lib => k8s.io/csi-translation-lib v0.36.1
-
-replace k8s.io/dynamic-resource-allocation => k8s.io/dynamic-resource-allocation v0.36.1
-
-replace k8s.io/endpointslice => k8s.io/endpointslice v0.36.1
-
-replace k8s.io/externaljwt => k8s.io/externaljwt v0.36.1
-
-replace k8s.io/kms => k8s.io/kms v0.36.1
-
-replace k8s.io/kube-aggregator => k8s.io/kube-aggregator v0.36.1
-
-replace k8s.io/kube-controller-manager => k8s.io/kube-controller-manager v0.36.1
-
-replace k8s.io/kube-proxy => k8s.io/kube-proxy v0.36.1
-
-replace k8s.io/kube-scheduler => k8s.io/kube-scheduler v0.36.1
-
 replace k8s.io/kubectl => k8s.io/kubectl v0.36.1
 
-replace k8s.io/kubelet => k8s.io/kubelet v0.36.1
-
-replace k8s.io/kubernetes => k8s.io/kubernetes v1.36.1
-
-replace k8s.io/metrics => k8s.io/metrics v0.36.1
-
-replace k8s.io/mount-utils => k8s.io/mount-utils v0.36.1
-
-replace k8s.io/pod-security-admission => k8s.io/pod-security-admission v0.36.1
-
-replace k8s.io/sample-apiserver => k8s.io/sample-apiserver v0.36.1
-
 replace k8s.io/streaming => k8s.io/streaming v0.36.1