default thumbnail size

mobile/lib/providers/image/immich_local_thumbnail_provider.dart

@@ -18,8 +18,8 @@ class ImmichLocalThumbnailProvider
 
   ImmichLocalThumbnailProvider({
     required this.asset,
-    this.height = 256,
+    this.height = 128,
-    this.width = 256,
+    this.width = 128,
   }) : assert(asset.local != null, 'Only usable when asset.local is set');
 
   /// Converts an [ImageProvider]'s settings plus an [ImageConfiguration] to a key

mobile/lib/widgets/common/immich_thumbnail.dart

@@ -31,7 +31,7 @@ class ImmichThumbnail extends HookWidget {
   static ImageProvider imageProvider({
     Asset? asset,
     String? assetId,
-    int thumbnailSize = 256,
+    int thumbnailSize = 128,
   }) {
     if (asset == null && assetId == null) {
       throw Exception('Must supply either asset or assetId');