Onboard repospawner UI to Authentik OIDC

Add an OAuth2/OIDC provider + application for the repospawner operator tool,
fronted by oauth2-proxy, and gate it on a new akP-repospawner-admin permission
group nested under akR-global-admin (mirrors the watchstate precedent).

config/permissions/akP-repospawner-admin.yaml

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

config/providers_oauth2/repospawner.yaml

@@ -0,0 +1,25 @@
+# OAuth2/OIDC provider + application for repospawner (the internal repository
+# provisioning admin tool, served at
+# https://repospawner.k8s.syd1.au.unkin.net (cluster hostname) and
+# https://repospawner.unkin.net (external hostname) in the repospawner 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-repospawner-admin).
+# client_secret is read from Vault (seeded out of band), never committed.
+name: repospawner
+authorization_flow: default-provider-authorization-implicit-consent
+invalidation_flow: default-provider-invalidation-flow
+client_type: confidential
+client_id: repospawner
+launch_url: https://repospawner.unkin.net/
+client_secret_vault:
+  mount: kv
+  path: kubernetes/namespace/repospawner/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://repospawner.k8s.syd1.au.unkin.net/oauth2/callback
+  - matching_mode: strict
+    url: https://repospawner.unkin.net/oauth2/callback

config/roles/akR-global-admin.yaml

@@ -8,6 +8,7 @@ permissions:
   - akP-traefik-admin
   - akP-logviewer-admin
   - akP-watchstate-admin
+  - akP-repospawner-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