Fix Nextcloud OIDC client_id/secret - was hardcoded empty

apps/nextcloud/values.yaml had oidc_login_client_id/secret as literal
empty strings, causing "client_id is missing or invalid" on login.
The matching Authentik blueprint (infrastructure/authentik/nextcloud-
blueprint.yaml) already defines fixed credentials for this OAuth2
provider - just never got copied over. Filled in to match.

Also found and left alone: an orphaned nextcloud-oidc-config ConfigMap
(from January) that already had the correct values but isn't actually
mounted by the current Deployment (which uses nextcloud-config instead)
- harmless dead resource, not the active config path.

apps/nextcloud/values.yaml

@@ -33,8 +33,8 @@ nextcloud:
         <?php
         $CONFIG = array (
           'oidc_login_provider_url' => 'https://auth.kube.huskypup.net/application/o/nextcloud/',
-          'oidc_login_client_id' => '',
-          'oidc_login_client_secret' => '',
+          'oidc_login_client_id' => 'HmTGnUfhCvjFFbUUAne7JLrucNC2X675JicPbEnQ',
+          'oidc_login_client_secret' => 'qTUf4NYjzUuAqfNV5D7SFPuuhJJwVltU6U3LAuJVy7dddJWeJSv2B4wKaRxbbHqpIiSfYPDaKujhEysKbOWUnf4n9OHPKJ0bu1I2EzkYtChO1Gq4gUv5EHPTzQlMBPnl',
           'oidc_login_button_text' => 'Log in with Authentik',
           'oidc_login_auto_redirect' => false,
           'oidc_login_hide_password_form' => false,