feat: Add PWA support and CORS configuration

- Configure VitePWA with manifest, icons and service worker
- Add PwaInstallBanner component for install prompt in header
- Enable CORS for z590.interno.com access
- Use dynamic hostname for terminal WebSocket connection
- Add generate-icons script with sharp for PWA icons
- Fix theme-color to match header background

frontend/src/pages/TerminalPage.vue

@@ -17,7 +17,7 @@ let fitAddon: FitAddon | null = null
 let socket: WebSocket | null = null
 let resizeObserver: ResizeObserver | null = null
 
-const WS_URL = 'ws://localhost:4103'
+const WS_URL = `ws://${window.location.hostname}:4103`
 
 function initTerminal() {
   if (!terminalContainer.value) return