fix: resolve analyzer warnings

- Fix empty catch block in track_provider.dart with comment
- Replace deprecated withOpacity() with withValues(alpha:) in library_settings_page.dart

lib/providers/track_provider.dart

@@ -556,7 +556,8 @@ class TrackNotifier extends Notifier<TrackState> {
       final tracks = List<Track>.from(state.tracks);
       tracks[index] = updatedTrack;
       state = state.copyWith(tracks: tracks);
-    } catch (e) {
+    } catch (_) {
+      // Silently ignore update failures - track may have been removed
     }
   }
 

lib/screens/settings/library_settings_page.dart

@@ -443,7 +443,7 @@ class _LibraryHeroCard extends StatelessWidget {
         boxShadow: [
           if (!isDark)
             BoxShadow(
-              color: colorScheme.shadow.withOpacity(0.05),
+              color: colorScheme.shadow.withValues(alpha: 0.05),
               blurRadius: 20,
               offset: const Offset(0, 4),
             ),
@@ -459,7 +459,7 @@ class _LibraryHeroCard extends StatelessWidget {
             child: Icon(
               Icons.library_music,
               size: 200,
-              color: colorScheme.primary.withOpacity(0.05),
+              color: colorScheme.primary.withValues(alpha: 0.05),
             ),
           ),
           Positioned(
@@ -470,7 +470,7 @@ class _LibraryHeroCard extends StatelessWidget {
               height: 150,
               decoration: BoxDecoration(
                 shape: BoxShape.circle,
-                color: colorScheme.secondaryContainer.withOpacity(0.3),
+                color: colorScheme.secondaryContainer.withValues(alpha: 0.3),
               ),
             ),
           ),
@@ -574,7 +574,7 @@ class _LibraryHeroCard extends StatelessWidget {
                       Icon(
                         Icons.history,
                         size: 14,
-                        color: colorScheme.onSurfaceVariant.withOpacity(0.7),
+                        color: colorScheme.onSurfaceVariant.withValues(alpha: 0.7),
                       ),
                       const SizedBox(width: 6),
                       Text(
@@ -583,7 +583,7 @@ class _LibraryHeroCard extends StatelessWidget {
                         ),
                         style: TextStyle(
                           fontSize: 12,
-                          color: colorScheme.onSurfaceVariant.withOpacity(0.7),
+                          color: colorScheme.onSurfaceVariant.withValues(alpha: 0.7),
                         ),
                       ),
                     ],