Fix Grafana root_url to match ops.eblu.me access domain

OAuth state cookie is set on the domain users visit (grafana.ops.eblu.me)
but Grafana was constructing callbacks from root_url (grafana.tail8d86e.ts.net),
causing "Missing saved oauth state" errors.

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

argocd/manifests/grafana/values.yaml

@@ -26,7 +26,7 @@ persistence:
 # Grafana configuration via grafana.ini
 grafana.ini:
   server:
-    root_url: https://grafana.tail8d86e.ts.net
+    root_url: https://grafana.ops.eblu.me
   security:
     # Embedding disabled - iframe approach didn't work well for Homepage
     allow_embedding: false