Add logviewer OAuth2 provider/application and akP-logviewer-admin permission

The ClickHouse log UI (logviewer) is being exposed at
https://logviewer.unkin.net behind oauth2-proxy in the logging namespace;
this adds the Authentik side as the prerequisite.

- Adds config/providers_oauth2/logviewer.yaml mirroring traefik: confidential
  client, client_id logviewer, secret from Vault kv
  kubernetes/namespace/logging/default/oauth-credentials,
  openid/email/profile scopes (ak_groups is attached to every oauth2
  provider by the module), strict redirect URI for the
  logviewer oauth2 callback.
- Adds config/permissions/akP-logviewer-admin.yaml bound to the logviewer
  application and nests it under akR-global-admin.

config/permissions/akP-logviewer-admin.yaml

@@ -0,0 +1,3 @@
+# Permission group akP-logviewer-admin (name = filename). Grants admin
+# access to logviewer: bound to the logviewer application, gating the log UI.
+application: logviewer

config/providers_oauth2/logviewer.yaml

@@ -0,0 +1,21 @@
+# OAuth2/OIDC provider + application for logviewer (the ClickHouse log UI,
+# served at https://logviewer.unkin.net in the logging namespace). An
+# oauth2-proxy in front of the UI performs the OIDC login; access is gated on
+# the user's hierarchical ak_groups claim (akP-logviewer-admin).
+# client_secret is read from Vault (seeded out of band), never committed.
+name: logviewer
+authorization_flow: default-provider-authorization-implicit-consent
+invalidation_flow: default-provider-invalidation-flow
+client_type: confidential
+client_id: logviewer
+launch_url: https://logviewer.unkin.net/
+client_secret_vault:
+  mount: kv
+  path: kubernetes/namespace/logging/default/oauth-credentials
+scope_mappings:
+  - goauthentik.io/providers/oauth2/scope-openid
+  - goauthentik.io/providers/oauth2/scope-email
+  - goauthentik.io/providers/oauth2/scope-profile
+redirect_uris:
+  - matching_mode: strict
+    url: https://logviewer.unkin.net/oauth2/callback

config/roles/akR-global-admin.yaml

@@ -4,6 +4,7 @@ permissions:
   - akP-argocd-admin
   - akP-rancher-admin
   - akP-litellm-admin
+  - akP-logviewer-admin
   # arrstack has no admin tier (it is a proxy front door); grant global admins
   # the front door plus every per-app entitlement so they reach all media apps.
   - akP-arrstack-user