vault: use public OIDC client for CLI localhost redirect support

terraform/vault/oidc.tf

@@ -1,10 +1,10 @@
 # OIDC authentication backend for Kanidm integration
+# Using a public client (no secret) to support CLI localhost redirects
 resource "vault_jwt_auth_backend" "oidc" {
   path               = "oidc"
   type               = "oidc"
   oidc_discovery_url = "https://auth.home.2rjus.net/oauth2/openid/openbao"
   oidc_client_id     = "openbao"
-  oidc_client_secret = random_password.auto_secrets["services/openbao/oauth2-client-secret"].result
   default_role       = "default"
 
   tune {