Onboard the artifactapi web UI to Authentik OIDC

Add the OAuth2/OIDC provider + application and the akP-artifactapi-admin
permission group gating it, nested under akR-global-admin.

config/permissions/akP-artifactapi-admin.yaml

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

config/providers_oauth2/artifactapi.yaml

@@ -0,0 +1,23 @@
+# OAuth2/OIDC provider + application for the artifactapi web UI
+# (https://artifactapi.k8s.syd1.au.unkin.net/ui in the artifactapi namespace).
+# An oauth2-proxy fronts ONLY /ui and /oauth2; access is gated on the user's
+# hierarchical ak_groups claim (akP-artifactapi-admin). The package-manager
+# surfaces (/api/v1, /api/v2, /v2, /terraform, /.well-known) are NOT behind this
+# provider -- yum, containerd, docker, terraform and CI cannot do a browser flow.
+# client_secret is read from Vault (seeded out of band), never committed.
+name: artifactapi
+authorization_flow: default-provider-authorization-implicit-consent
+invalidation_flow: default-provider-invalidation-flow
+client_type: confidential
+client_id: artifactapi
+launch_url: https://artifactapi.k8s.syd1.au.unkin.net/ui/
+client_secret_vault:
+  mount: kv
+  path: kubernetes/namespace/artifactapi/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://artifactapi.k8s.syd1.au.unkin.net/oauth2/callback

config/roles/akR-global-admin.yaml

@@ -10,6 +10,7 @@ permissions:
   - akP-watchstate-admin
   - akP-repospawner-admin
   - akP-vault-admin
+  - akP-artifactapi-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