grafana: add Grafana on monitoring02 with Kanidm OIDC

Deploy Grafana test instance on monitoring02 with:
- Kanidm OIDC authentication (admins -> Admin role, others -> Viewer)
- PKCE enabled for secure OAuth2 flow (required by Kanidm)
- Declarative datasources for Prometheus and Loki on monitoring01
- Local Caddy for TLS termination via internal ACME CA
- DNS CNAME grafana-test.home.2rjus.net

Terraform changes add OAuth2 client secret and AppRole policies for
kanidm01 and monitoring02.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

terraform/vault/approle.tf

@@ -89,6 +89,23 @@ locals {
       ]
     }
 
+    # kanidm01: Kanidm identity provider
+    "kanidm01" = {
+      paths = [
+        "secret/data/hosts/kanidm01/*",
+        "secret/data/kanidm/*",
+        "secret/data/services/grafana/*",
+      ]
+    }
+
+    # monitoring02: Grafana test instance
+    "monitoring02" = {
+      paths = [
+        "secret/data/hosts/monitoring02/*",
+        "secret/data/services/grafana/*",
+      ]
+    }
+
   }
 }