grafana: deploy Grafana instance, datasource and dashboards (#238)

## Why
Deploys Grafana in-cluster (observability project) via the grafana-operator, mirroring the puppet Grafana but modernised — **CNPG** for state, **Authentik OIDC** for auth — and ports the live datasource + dashboards in as CRs.

Depends on: grafana-operator (#235, merged), grafana schemas (#236, merged), Authentik OIDC (terraform-authentik #2), Vault seeds (done), and `^grafana/` image proxy (terraform-artifactapi #5).

## Changes (`apps/base/grafana`)
- **CNPG** postgres Cluster + rw Pooler (db `grafana`); **VaultAuth** + **VaultStaticSecrets** pulling `postgres`/`oauth` credentials from `kv/kubernetes/namespace/grafana/default/*`.
- **Grafana CR**: postgres backend via the pooler; Authentik `generic_oauth` (client id/secret from the Vault-synced secret, openid/email/profile scopes, group→role mapping); `root_url` grafana.k8s.syd1.au.unkin.net.
- **1 GrafanaDatasource** — k8s VictoriaMetrics via the operator `vmselect-main` service; reuses the previous default datasource uid so the imported dashboards resolve unedited.
- **13 GrafanaDashboards** (gzipJson) exported from the current grafana.
- **Gateway API** (traefik-internal) + HTTPRoute for grafana.k8s.syd1.au.unkin.net.
- Registered in the observability ApplicationSet + project.

## Review notes
- OAuth `role_attribute_path` maps Authentik group `grafana-admins` → Admin, else Viewer — **confirm the group name**.
- `database.ssl_mode: require` against the CNPG pooler — adjust if the pooler isn't serving TLS.
- The `VictoriaLogs - cluster` dashboard has no in-cluster logs datasource yet (no VictoriaLogs in k8s) — included for completeness, will be empty until one exists.
- `make kubeconform` clean (24 resources, validated against the strict grafana schemas).

Reviewed-on: #238
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>

apps/base/grafana/dashboards/frr-ospf-route-metrics.yaml

@@ -0,0 +1,13 @@
+---
+apiVersion: grafana.integreatly.org/v1beta1
+kind: GrafanaDashboard
+metadata:
+  name: frr-ospf-route-metrics
+  namespace: grafana
+spec:
+  instanceSelector:
+    matchLabels:
+      dashboards: "grafana"
+  resyncPeriod: 5m
+  allowCrossNamespaceImport: false
+  gzipJson: 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