improve iOS Safari LiveView reliability

increase longPollFallbackMs from 2500 to 5000 to prevent premature
fallback on mobile networks, and add visibilitychange handler to
reconnect WebSocket when returning from a backgrounded tab

assets/js/app.ts

@@ -1205,7 +1205,7 @@ const StatusTitle = {
 }
 
 const liveSocket = new LiveSocket("/live", Socket, {
-  longPollFallbackMs: 2500,
+  longPollFallbackMs: 5000,
   params: { _csrf_token: csrfToken, timezone: userTimezone },
   hooks: { ...colocatedHooks, SensorChart, CopyToClipboard, ScrollToTop, AutoDismissFlash, BetaBannerDismiss, NetworkMap, SitesMap, LeafletMap, DeviceListReorder, MikrotikPortSync, GlobalSearch, GlobalSearchTrigger, DynamicFavicon, StatusTitle },
 })
@@ -1266,6 +1266,15 @@ window.addEventListener("phx:download", (event: any) => {
   window.URL.revokeObjectURL(url)
 })
 
+// Reconnect WebSocket when returning from background (iOS Safari optimization)
+document.addEventListener("visibilitychange", () => {
+  if (document.visibilityState === "visible") {
+    if (liveSocket.socket.connectionState() !== "open") {
+      liveSocket.socket.disconnect(() => liveSocket.socket.connect())
+    }
+  }
+})
+
 // connect if there are any LiveViews on the page
 liveSocket.connect()