fix(cover): preserve provider high-resolution artwork

lib/utils/cover_art_utils.dart

@@ -3,8 +3,9 @@ final RegExp _deezerCoverSizeRegex = RegExp(
   r'/(\d+)x(\d+)-(\d+)-(\d+)-(\d+)-(\d+)\.jpg$',
 );
 
-/// Upgrades a Spotify/Deezer cover URL to a display-quality resolution
-/// (Spotify 300px → 640px, Deezer → 1000x1000 preserving quality params).
+/// Upgrades a Spotify/Deezer cover URL to a display-quality resolution.
+/// Existing Deezer URLs at or above 1000px are preserved so provider
+/// extensions can supply higher-resolution artwork without being downgraded.
 /// Non-matching URLs pass through unchanged.
 String? highResCoverUrl(String? url) {
   if (url == null) return null;
@@ -13,10 +14,12 @@ String? highResCoverUrl(String? url) {
   }
   if (url.contains('cdn-images.dzcdn.net') &&
       _deezerCoverSizeRegex.hasMatch(url)) {
-    return url.replaceAllMapped(
-      _deezerCoverSizeRegex,
-      (m) => '/1000x1000-${m[3]}-${m[4]}-${m[5]}-${m[6]}.jpg',
-    );
+    return url.replaceAllMapped(_deezerCoverSizeRegex, (m) {
+      final width = int.tryParse(m[1] ?? '') ?? 0;
+      final height = int.tryParse(m[2] ?? '') ?? 0;
+      if (width >= 1000 && height >= 1000) return m[0]!;
+      return '/1000x1000-${m[3]}-${m[4]}-${m[5]}-${m[6]}.jpg';
+    });
   }
   return url;
 }

test/cover_art_utils_test.dart

@@ -0,0 +1,31 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:spotiflac_android/utils/cover_art_utils.dart';
+
+void main() {
+  group('highResCoverUrl', () {
+    test('upgrades a small Deezer cover to display quality', () {
+      expect(
+        highResCoverUrl(
+          'https://cdn-images.dzcdn.net/images/cover/hash/'
+          '250x250-000000-80-0-0.jpg',
+        ),
+        'https://cdn-images.dzcdn.net/images/cover/hash/'
+        '1000x1000-000000-80-0-0.jpg',
+      );
+    });
+
+    test('does not downgrade provider-supplied Deezer artwork', () {
+      const url =
+          'https://cdn-images.dzcdn.net/images/cover/hash/'
+          '1400x1400-000000-80-0-0.jpg';
+      expect(highResCoverUrl(url), url);
+    });
+
+    test('still upgrades a Spotify 300px cover to 640px', () {
+      expect(
+        highResCoverUrl('https://i.scdn.co/image/ab67616d00001e02abcdef'),
+        'https://i.scdn.co/image/ab67616d0000b273abcdef',
+      );
+    });
+  });
+}