fix: restore owner-scoped gateway startup (#1625)

* fix: restore owner-scoped gateway startup

* fix: split gateway owner and sender scope

* fix: keep multi-user gateway sender identity

* test: cover gateway sender scope regression

* test: harden e2e startup teardown race

* fix: align gateway owner scope across auth modes

tests/support/gateway_workflow_harness.rs

@@ -226,7 +226,8 @@ impl GatewayWorkflowHarness {
             job_manager: None,
             prompt_queue: None,
             scheduler: Some(scheduler_slot.clone()),
-            default_user_id: user_id.clone(),
+            owner_id: user_id.clone(),
+            default_sender_id: user_id.clone(),
             shutdown_tx: tokio::sync::RwLock::new(None),
             ws_tracker: Some(Arc::new(WsConnectionTracker::new())),
             llm_provider: Some(Arc::clone(&components.llm)),