chore(07-01): add ArgoCD repository secret documentation

- Document taskplaner-repo secret structure for ArgoCD
- Secret created via kubectl (not committed) for security
- Uses internal cluster URL for Gitea access

argocd/repo-secret.yaml

@@ -0,0 +1,22 @@
+# ArgoCD Repository Secret for TaskPlanner
+# This file documents the secret structure. Apply using kubectl, not this file.
+#
+# To create the secret:
+# PASSWORD=$(kubectl get secret gitea-repo -n argocd -o jsonpath='{.data.password}' | base64 -d)
+# cat <<EOF | kubectl apply -f -
+# apiVersion: v1
+# kind: Secret
+# metadata:
+#   name: taskplaner-repo
+#   namespace: argocd
+#   labels:
+#     argocd.argoproj.io/secret-type: repository
+# stringData:
+#   type: git
+#   url: http://gitea-http.gitea.svc.cluster.local:3000/tho/taskplaner.git
+#   username: admin
+#   password: "$PASSWORD"
+# EOF
+#
+# The secret allows ArgoCD to access the TaskPlanner Git repository
+# using internal cluster networking (gitea-http.gitea.svc.cluster.local).