feat: add kubeadm bootstrap, Argo CD root app and lab RBAC

Terraform 설계서 7.2·7.3의 WP-07 내용.

- bootstrap/kubeadm/init-cp.sh: kubeadm init(사설 IP advertise, EIP cert SAN,
  pod CIDR 10.244.0.0/16) → flannel v0.28.9 → Argo CD v3.5.3(server-side apply)
  → root-app 적용 → 워커 join 명령을 /opt/selfheal/join.sh(0600)에 저장. 재실행 안전.
- bootstrap/kubeadm/join-worker.sh: join 명령을 stdin으로 받아 실행(토큰이 터미널·로그에
  남지 않음). 이미 join된 노드는 0으로 종료.
- argocd/root-app.yaml: apps/ 재귀 app-of-apps(공개 저장소, 자격증명 불요).
- apps/rbac.yaml + workloads/rbac: 네임스페이스 chaos-mesh·demo, SA harness(ClusterRole
  selfheal-harness: chaos-mesh.org/*, deployments·scale, pods, nodes patch, pods/eviction),
  SA ai-reader(ClusterRole view).

argocd/root-app.yaml

@@ -0,0 +1,26 @@
+# app-of-apps root (Terraform design 7.2 / 7.3). Applied once by init-cp.sh; everything under apps/ is then Git-driven.
+# The gitops repository is public, so no repository credential is needed.
+apiVersion: argoproj.io/v1alpha1
+kind: Application
+metadata:
+  name: root
+  namespace: argocd
+  finalizers:
+    - resources-finalizer.argocd.argoproj.io
+spec:
+  project: default
+  source:
+    repoURL: https://git.seonology.com/selfheal-lab/selfheal-lab-gitops.git
+    targetRevision: main
+    path: apps
+    directory:
+      recurse: true
+  destination:
+    server: https://kubernetes.default.svc
+    namespace: argocd
+  syncPolicy:
+    automated:
+      prune: true
+      selfHeal: true
+    syncOptions:
+      - ServerSideApply=true