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/global-teardown.ts

@@ -1,5 +1,7 @@
+import { teardownDiscoverSpreadStub } from './discover-spread-stub';
 import { teardownLiveStubAgent } from './live-stub';
 
 export default function globalTeardown(): void {
+  teardownDiscoverSpreadStub();
   teardownLiveStubAgent();
 }