fix(#76): correct frontend availability, retry, and live recovery semantics

Make response freshness React Query-safe, retry the failed Weekend/Preview/Briefing resources with busy gating, preserve distinct embedded Preview notices, and clear fatal Live errors once SSE supplies usable timing.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/main.tsx

@@ -1,19 +1,12 @@
 import React from 'react'
 import ReactDOM from 'react-dom/client'
 import { RouterProvider } from '@tanstack/react-router'
-import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
+import { QueryClientProvider } from '@tanstack/react-query'
+import { createAppQueryClient } from './lib/queryClient'
 import { router } from './router'
 import './styles/app.css'
 
-const queryClient = new QueryClient({
-  defaultOptions: {
-    queries: {
-      staleTime: 30_000,
-      // Explicit Retry on RouteState — avoid automatic retry storms.
-      retry: false,
-    },
-  },
-})
+const queryClient = createAppQueryClient()
 
 ReactDOM.createRoot(document.getElementById('root')!).render(
   <React.StrictMode>