chore: ignore renovate-token secret diff in ArgoCD

Prevents ArgoCD from overwriting the real token with the placeholder.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

renovate/argocd-app.yaml

@@ -12,6 +12,12 @@ spec:
   destination:
     server: https://kubernetes.default.svc
     namespace: renovate
+  ignoreDifferences:
+  - group: ""
+    kind: Secret
+    name: renovate-token
+    jsonPointers:
+    - /data
   syncPolicy:
     automated:
       prune: true