Add ArgoCD GitOps bootstrap contract for railiance01

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.

argocd/repositories/issue-core.repository.sops.yaml.template

@@ -0,0 +1,21 @@
+# Copy to issue-core.repository.sops.yaml, fill from the approved
+# operator/OpenBao path, then encrypt with:
+#   sops -e -i argocd/repositories/issue-core.repository.sops.yaml
+#
+# Do not commit plaintext credentials.
+apiVersion: v1
+kind: Secret
+metadata:
+  name: issue-core-repository
+  namespace: argocd
+  labels:
+    argocd.argoproj.io/secret-type: repository
+    app.kubernetes.io/part-of: railiance-gitops
+    railiance-platform/component: gitops
+stringData:
+  type: git
+  project: railiance-tenants
+  url: https://gitea.coulomb.social/coulomb/issue-core.git
+  username: CHANGE_ME
+  password: CHANGE_ME
+