feat: optimize sleep timer state management in NowPlayingPage

Author: gokadzev

lib/screens/now_playing_page.dart

@@ -551,10 +551,6 @@ class NowPlayingPage extends StatelessWidget {
                               if (hours > 0) {
                                 setState(() {
                                   hours--;
-                                  sleepTimerNotifier.value = Duration(
-                                    hours: hours,
-                                    minutes: minutes,
-                                  );
                                 });
                               }
                             },
@@ -565,10 +561,6 @@ class NowPlayingPage extends StatelessWidget {
                             onPressed: () {
                               setState(() {
                                 hours++;
-                                sleepTimerNotifier.value = Duration(
-                                  hours: hours,
-                                  minutes: minutes,
-                                );
                               });
                             },
                           ),
@@ -589,10 +581,6 @@ class NowPlayingPage extends StatelessWidget {
                               if (minutes > 0) {
                                 setState(() {
                                   minutes--;
-                                  sleepTimerNotifier.value = Duration(
-                                    hours: hours,
-                                    minutes: minutes,
-                                  );
                                 });
                               }
                             },
@@ -603,10 +591,6 @@ class NowPlayingPage extends StatelessWidget {
                             onPressed: () {
                               setState(() {
                                 minutes++;
-                                sleepTimerNotifier.value = Duration(
-                                  hours: hours,
-                                  minutes: minutes,
-                                );
                               });
                             },
                           ),
@@ -626,6 +610,10 @@ class NowPlayingPage extends StatelessWidget {
                     final duration = Duration(hours: hours, minutes: minutes);
                     if (duration.inSeconds > 0) {
                       audioHandler.setSleepTimer(duration);
+                      sleepTimerNotifier.value = Duration(
+                        hours: hours,
+                        minutes: minutes,
+                      );
                       showToast(context, context.l10n!.addedSuccess);
                     }
                     Navigator.pop(context);