fix(library): preserve cached covers across directory aliases

lib/providers/local_library_provider.dart

@@ -4,6 +4,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:path_provider/path_provider.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 import 'package:spotiflac_android/providers/settings_provider.dart';
+import 'package:spotiflac_android/services/library_cleanup.dart';
 import 'package:spotiflac_android/services/library_database.dart';
 import 'package:spotiflac_android/services/notification_service.dart';
 import 'package:spotiflac_android/services/platform_bridge.dart';
@@ -1203,23 +1204,10 @@ class LocalLibraryNotifier extends Notifier<LocalLibraryState> {
         offset += pageSize;
       }
 
-      var deletedCount = 0;
-      await for (final entity in libraryCoverDir.list(
-        recursive: true,
-        followLinks: false,
-      )) {
-        if (entity is! File || referencedCoverPaths.contains(entity.path)) {
-          continue;
-        }
-        try {
-          await entity.delete();
-          deletedCount++;
-        } catch (e) {
-          _log.w(
-            'Failed deleting stale library cover cache ${entity.path}: $e',
-          );
-        }
-      }
+      final deletedCount = await pruneUnreferencedLibraryCovers(
+        libraryCoverDir,
+        referencedCoverPaths,
+      );
 
       if (deletedCount > 0) {
         _log.i('Pruned $deletedCount stale library cover cache files');

lib/services/library_cleanup.dart

@@ -1,5 +1,39 @@
+import 'dart:io';
 import 'package:sqflite/sqflite.dart';
 import 'package:spotiflac_android/utils/file_access.dart';
+import 'package:spotiflac_android/utils/logger.dart';
+
+Future<int> pruneUnreferencedLibraryCovers(
+  Directory directory,
+  Set<String> referencedPaths,
+) async {
+  // Native scans may return canonical paths while Dart lists a directory alias.
+  final retainedPaths = {...referencedPaths};
+  for (final path in referencedPaths) {
+    try {
+      retainedPaths.add(await File(path).resolveSymbolicLinks());
+    } on FileSystemException {
+      // Missing cache files can remain referenced until the next full scan.
+    }
+  }
+  var deleted = 0;
+  await for (final entity in directory.list(
+    recursive: true,
+    followLinks: false,
+  )) {
+    if (entity is! File || retainedPaths.contains(entity.path)) continue;
+    try {
+      if (retainedPaths.contains(await entity.resolveSymbolicLinks())) continue;
+      await entity.delete();
+      deleted++;
+    } catch (error) {
+      final message =
+          'Failed deleting stale library cover cache ${entity.path}: $error';
+      AppLogger('LocalLibrary').w(message);
+    }
+  }
+  return deleted;
+}
 
 /// Pages by stable ID (not OFFSET, since rows are removed during traversal).
 /// A high-water mark bounds the run if a concurrent scan adds new rows.