fix(library): keep album batch actions alive after selection closes

Use the album screen context for ReplayGain and conversion so dismissing the selection overlay does not invalidate the pending operation. Cover local and downloaded albums in both themes.

lib/screens/downloaded_album_screen.dart

@@ -738,7 +738,7 @@ class _DownloadedAlbumScreenState extends ConsumerState<DownloadedAlbumScreen>
                 label: context.l10n.selectionConvertCount(selectedCount),
                 onPressed: selectedCount > 0
                     ? () => showBatchConvertSheet(
-                        context,
+                        this.context,
                         ref,
                         _selectedUnifiedItems(tracks),
                         onExitSelectionMode: exitSelectionMode,
@@ -751,7 +751,7 @@ class _DownloadedAlbumScreenState extends ConsumerState<DownloadedAlbumScreen>
                 label: context.l10n.selectionReplayGainCount(selectedCount),
                 onPressed: selectedCount > 0
                     ? () => runBatchReplayGain(
-                        context,
+                        this.context,
                         _selectedUnifiedItems(tracks),
                         onExitSelectionMode: exitSelectionMode,
                       )

lib/screens/local_album_screen.dart

@@ -547,7 +547,7 @@ class _LocalAlbumScreenState extends ConsumerState<LocalAlbumScreen>
                 label: context.l10n.selectionConvertCount(selectedCount),
                 onPressed: selectedCount > 0
                     ? () => showBatchConvertSheet(
-                        context,
+                        this.context,
                         ref,
                         _selectedUnifiedItems(tracks),
                         onExitSelectionMode: exitSelectionMode,
@@ -563,7 +563,7 @@ class _LocalAlbumScreenState extends ConsumerState<LocalAlbumScreen>
                 label: context.l10n.selectionReplayGainCount(selectedCount),
                 onPressed: selectedCount > 0
                     ? () => runBatchReplayGain(
-                        context,
+                        this.context,
                         _selectedUnifiedItems(tracks),
                         onExitSelectionMode: exitSelectionMode,
                       )