Remove interim ClusterSecretStores (forgejo, activity-core, reuse) from
coulombcore ArgoCD kustomization. Those stores target railiance01 namespaces
and are bootstrapped via railiance-apps/activity-core Make targets.
Define platform-owned AppProjects, root app-of-apps, repository registration
templates, and tenant onboarding docs so issue-core can deploy via ArgoCD.
Ignore encrypted repository secrets locally and cross-link OpenBao delivery
guidance with the new GitOps contract.