Add web app manifest for improved PWA support with icons

frontend/index.html

@@ -2,10 +2,12 @@
 <html lang="ru">
   <head>
     <meta charset="UTF-8" />
-    <link rel="icon" type="image/svg+xml" href="/bus-icon.svg" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <meta name="description" content="RideBus DE Admin Panel" />
     <title>RideBus DE Admin</title>
+    <link rel="manifest" href="/manifest.json" />
+    <link rel="icon" href="/favicon.ico" sizes="any">
+    <link rel="apple-touch-icon" href="/apple-touch-icon.png">
     
     <!-- Leaflet CSS -->
     <link rel="stylesheet" href="https://unpkg.com/leaflet@1.9.4/dist/leaflet.css" />