feat(web): wire up MCP task support — Tasks screen, Run-as-task, status toasts (#1422) (#1424)

Wires the ported Tasks screen + core task subsystem through App.tsx: sticky Clear Completed, cancel/refresh error toasts, core-side per-task progress correlation, Run-as-task on the Tools screen (gated on server support), per-server Task TTL, and live task-status toasts.

clients/web/src/test/integration/mcp/remote/transport.test.ts

@@ -410,6 +410,7 @@ describe("Remote transport e2e", () => {
         metadata: [],
         connectionTimeout: 0,
         requestTimeout: 0,
+        taskTtl: 0,
       };
 
       const createTransport = createRemoteTransport({ baseUrl, authToken });