fix: core-cli OAuth2 + S3 backend + admin group

- Link core-cli app to OAuth2 provider (was hardcoded to 0)
- Add core-cli user to authentik_admins for CI access
- Fix terraform init: use 'endpoint' not 'endpoints.s3' for S3 backend
  (Terraform 1.9.4 compatibility, matches state.tf config)

terraform/state.tf

@@ -4,9 +4,7 @@ terraform {
     bucket                      = "terraform-state"
     key                         = "homelab/terraform.tfstate"
     region                      = "us-east-1"
-    endpoints = {
-      s3 = "https://minio-api.riotpiao.homelab.com"
-    }
+    endpoint = "https://minio-api.riotpiao.homelab.com"
     profile                     = "minio"
     skip_credentials_validation = true
     skip_requesting_account_id  = true