perf: ottimizzato il controllo degli aggiornamenti PWA all'avvio e al ripristino dell'app

- Implementato il controllo immediato non appena l'applicazione Angular si stabilizza (isStable).
- Aggiunto il controllo reattivo al cambio di visibilità (document visibilityState === visible) quando la PWA viene riportata in primo piano/focalizzata.
- Mantendo il controllo periodico in background ogni 5 minuti.

src/app/app.component.ts

@@ -1,7 +1,7 @@
 import { Component, inject, ApplicationRef } from '@angular/core';
 import { SwUpdate, VersionReadyEvent } from '@angular/service-worker';
 import { filter, first } from 'rxjs/operators';
-import { concat, interval } from 'rxjs';
+import { concat, interval, fromEvent } from 'rxjs';
 
 @Component({
   selector: 'app-root',
@@ -19,14 +19,44 @@ export class AppComponent {
 
   private setupUpdates() {
     if (this.swUpdate.isEnabled) {
-      // Controlla aggiornamenti ogni 5 minuti invece di 30
-      const everyFiveMinutes$ = interval(5 * 60 * 1000);
-      
-      everyFiveMinutes$.subscribe(() => {
-        console.log('Checking for PWA updates...');
-        this.swUpdate.checkForUpdate();
+      // 1. Check for updates immediately as soon as the application stabilizes
+      const appIsStable$ = this.appRef.isStable.pipe(
+        first(isStable => isStable === true)
+      );
+
+      appIsStable$.subscribe(async () => {
+        console.log('[PWA-Update] App is stable, checking for PWA updates immediately...');
+        try {
+          await this.swUpdate.checkForUpdate();
+        } catch (err) {
+          console.warn('[PWA-Update] Failed startup update check:', err);
+        }
       });
 
+      // 2. Check for updates when the app is resumed/focused
+      fromEvent(document, 'visibilitychange')
+        .pipe(filter(() => document.visibilityState === 'visible'))
+        .subscribe(async () => {
+          console.log('[PWA-Update] App resumed, checking for PWA updates...');
+          try {
+            await this.swUpdate.checkForUpdate();
+          } catch (err) {
+            console.warn('[PWA-Update] Failed visible resume update check:', err);
+          }
+        });
+
+      // 3. Periodic check in background every 5 minutes
+      const everyFiveMinutes$ = interval(5 * 60 * 1000);
+      everyFiveMinutes$.subscribe(async () => {
+        console.log('[PWA-Update] Periodic check for updates...');
+        try {
+          await this.swUpdate.checkForUpdate();
+        } catch (err) {
+          console.warn('[PWA-Update] Failed periodic update check:', err);
+        }
+      });
+
+      // 4. Activate update and reload when a new version is ready
       this.swUpdate.versionUpdates
         .pipe(filter((evt): evt is VersionReadyEvent => evt.type === 'VERSION_READY'))
         .subscribe(() => {