feat: allinea lo swipe e lo scroll con l'avanzamento karaoke, aggiungi frecce di navigazione canti nel titolo

src/app/services/settings.service.ts

@@ -50,6 +50,9 @@ export class SettingsService {
   /** Preferenza notazione accordi: diesis o bemolle */
   public chordNotationPreference = signal<'diesis' | 'bemolle'>('diesis');
 
+  /** Avanzamento a pagine del karaoke manuale: true = i tasti next/prev voltano la pagina */
+  public karaokePageScrollMode = signal<boolean>(false);
+
   private wakeLock: any = null;
 
   // PWA installation signals
@@ -198,6 +201,13 @@ export class SettingsService {
       this.chordNotationPreference.set('diesis');
     }
 
+    const savedKaraokePageScrollMode = localStorage.getItem('karaoke-page-scroll-mode');
+    if (savedKaraokePageScrollMode !== null) {
+      this.karaokePageScrollMode.set(savedKaraokePageScrollMode === 'true');
+    } else {
+      this.karaokePageScrollMode.set(false);
+    }
+
     // Sync browser fullscreen state with listeners (supporting vendor prefixes)
     const updateFullscreenState = () => {
       const isFs = !!(
@@ -270,6 +280,10 @@ export class SettingsService {
       localStorage.setItem('chord-notation-preference', this.chordNotationPreference());
     });
 
+    effect(() => {
+      localStorage.setItem('karaoke-page-scroll-mode', this.karaokePageScrollMode().toString());
+    });
+
     effect(() => {
       const active = this.keepScreenOn();
       localStorage.setItem('keep-screen-on', active.toString());
@@ -396,6 +410,12 @@ export class SettingsService {
     localStorage.setItem('enable-acoustic-autoscroll', newValue.toString());
   }
 
+  toggleKaraokePageScrollMode() {
+    const newValue = !this.karaokePageScrollMode();
+    this.karaokePageScrollMode.set(newValue);
+    localStorage.setItem('karaoke-page-scroll-mode', newValue.toString());
+  }
+
   setChordNotationPreference(val: 'diesis' | 'bemolle') {
     this.chordNotationPreference.set(val);
   }