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

frontend/src/main.tsx

@@ -3,18 +3,6 @@ import { createRoot } from 'react-dom/client'
 import './index.css'
 import App from './App.tsx'
 
-if ('serviceWorker' in navigator) {
-  window.addEventListener('load', () => {
-    navigator.serviceWorker.register('/sw.js', { scope: '/' })
-      .then((registration) => {
-        console.log('SW registered:', registration)
-      })
-      .catch((error) => {
-        console.log('SW registration failed:', error)
-      })
-  })
-}
-
 createRoot(document.getElementById('root')!).render(
   <StrictMode>
     <App />