feat(sync): live cross-module cache invalidation (no manual refresh)

- procurement store refreshes right after a warehouse receipt (arrivals) and
  after role/project changes (organization/admin), so the ledger reflects
  warehouse actions immediately
- refetchOnWindowFocus enabled on the shared query client
- BroadcastChannel (lib/crossTab.ts): mutations broadcast 'quotes' /
  'inventory'; all warehouse pages + the store hook resync open tabs
  automatically (receipt in one tab updates the ledger in another)
- warehouse mutations (stock changes) notify other tabs; same-page refresh
  behavior unchanged

frontend/src/main.tsx

@@ -1,19 +1,11 @@
 import { StrictMode } from "react";
 import { createRoot } from "react-dom/client";
 import { BrowserRouter } from "react-router-dom";
-import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+import { QueryClientProvider } from "@tanstack/react-query";
 import { Toaster } from "sonner";
 import App from "./App";
 import "./styles/globals.css";
-
-const queryClient = new QueryClient({
-  defaultOptions: {
-    queries: {
-      retry: false,
-      refetchOnWindowFocus: false,
-    },
-  },
-});
+import { queryClient } from "./lib/queryClient";
 
 createRoot(document.getElementById("root")!).render(
   <StrictMode>