perf(player): reuse artwork decodes across Mornye transitions

lib/screens/now_playing_screen.dart

@@ -263,6 +263,7 @@ class _NowPlayingScreenState extends ConsumerState<NowPlayingScreen> {
                 ? PlayerArtwork(
                     artUri: mediaItem.artUri?.toString(),
                     colorScheme: colorScheme,
+                    cacheWidth: PlayerArtwork.transitionCacheWidth(context),
                   )
                 : artwork(),
           ),

lib/widgets/mornye_player_artwork.dart

@@ -41,10 +41,7 @@ class _MornyePlayerArtworkState extends ConsumerState<MornyePlayerArtwork> {
         child: PlayerArtwork(
           artUri: widget.mediaItem.artUri?.toString(),
           colorScheme: Theme.of(context).colorScheme,
-          cacheWidth:
-              (MediaQuery.sizeOf(context).width *
-                      MediaQuery.devicePixelRatioOf(context))
-                  .round(),
+          cacheWidth: PlayerArtwork.transitionCacheWidth(context),
         ),
       ),
     );

lib/widgets/mornye_player_layout.dart

@@ -333,11 +333,9 @@ class MornyePlayerLayout extends ConsumerWidget {
                                                           ?.toString(),
                                                       colorScheme: colorScheme,
                                                       cacheWidth:
-                                                          (360 *
-                                                                  MediaQuery.devicePixelRatioOf(
-                                                                    context,
-                                                                  ))
-                                                              .round(),
+                                                          PlayerArtwork.transitionCacheWidth(
+                                                            context,
+                                                          ),
                                                     ),
                                                   ),
                                                 ),

lib/widgets/player_artwork.dart

@@ -20,6 +20,12 @@ class PlayerArtwork extends StatelessWidget {
     this.iconSize = 40,
   });
 
+  /// Share one full-size decode while artwork moves between player panels.
+  static int transitionCacheWidth(BuildContext context) =>
+      (MediaQuery.sizeOf(context).width *
+              MediaQuery.devicePixelRatioOf(context))
+          .round();
+
   @override
   Widget build(BuildContext context) {
     final placeholder = Container(