Stabilize Playwright phase 8 E2E to 25 green specs.

Harden login and online-card assertions, fix multi-hop discover spread selection, add Path Tracer RS lanes mock E2E, and graceful stub WS teardown.

server/web/e2e/stub-agent.ts

@@ -139,6 +139,8 @@ export async function connectStubAgent(
 
   return () => {
     clearInterval(statsTimer);
-    ws.close();
+    if (ws.readyState === WebSocket.OPEN || ws.readyState === WebSocket.CONNECTING) {
+      ws.close(1000, 'e2e-teardown');
+    }
   };
 }