feat(player): continue playback with Library autoplay

lib/screens/main_shell.dart

@@ -92,6 +92,10 @@ class _MainShellState extends ConsumerState<MainShell>
       ref.read(settingsProvider).playbackNormalization,
     );
     setAutoMixEnabled(ref.read(settingsProvider).autoMix);
+    setAutoplayEnabled(
+      ref.read(settingsProvider).autoplay,
+      includeLocal: ref.read(settingsProvider).localLibraryEnabled,
+    );
     // Deezer & co. localize artist/genre names by IP unless told the app's
     // language (issue #480).
     unawaited(
@@ -738,6 +742,10 @@ class _MainShellState extends ConsumerState<MainShell>
     ref.listen(settingsProvider.select((s) => s.autoMix), (_, enabled) {
       setAutoMixEnabled(enabled);
     });
+    ref.listen(
+      settingsProvider.select((s) => (s.autoplay, s.localLibraryEnabled)),
+      (_, value) => setAutoplayEnabled(value.$1, includeLocal: value.$2),
+    );
     final queueState = ref.watch(
       downloadQueueProvider.select((s) => s.queuedCount),
     );

lib/screens/now_playing_screen.dart

@@ -2356,6 +2356,9 @@ class _NowPlayingScreenState extends ConsumerState<NowPlayingScreen> {
                   ),
                 );
                 final textTheme = Theme.of(context).textTheme;
+                final autoplay = ref.watch(
+                  settingsProvider.select((s) => s.autoplay),
+                );
 
                 return Column(
                   children: [
@@ -2371,6 +2374,17 @@ class _NowPlayingScreenState extends ConsumerState<NowPlayingScreen> {
                             ),
                           ),
                           const Spacer(),
+                          IconButton(
+                            tooltip: autoplay
+                                ? context.l10n.autoplayOn
+                                : context.l10n.autoplayOff,
+                            isSelected: autoplay,
+                            icon: const Icon(Icons.all_inclusive),
+                            color: autoplay ? colorScheme.primary : null,
+                            onPressed: () => ref
+                                .read(settingsProvider.notifier)
+                                .setAutoplay(!autoplay),
+                          ),
                           IconButton(
                             tooltip: switch (repeatMode) {
                               AudioServiceRepeatMode.one =>