refine nginx caching strategy and add service worker update prompt with periodic checks

frontend/src/App.tsx

@@ -4,6 +4,7 @@ import { DeliveryForm } from './components/delivery/DeliveryForm';
 import { LoginForm } from './components/auth/LoginForm';
 import { ToastContainer } from './components/ui/Toast';
 import { Button } from './components/ui/Button';
+import { UpdatePrompt } from './components/ui/UpdatePrompt';
 import { useDeliveryStore } from './stores/deliveryStore';
 import { useAuthStore } from './stores/authStore';
 
@@ -89,6 +90,7 @@ function App() {
   if (!isAuthenticated) {
     return (
       <>
+        <UpdatePrompt />
         <LoginForm />
         <ToastContainer />
       </>
@@ -97,6 +99,7 @@ function App() {
 
   return (
     <div className="min-h-screen bg-[#fbf8fb]">
+      <UpdatePrompt />
       <header className="sticky top-0 z-40 bg-[#1B263B] text-white shadow-md">
         <div className="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8">
           <div className="flex items-center justify-between h-14">