feat: 根据设备像素比调整画廊列表卡片和缩略图组件的尺寸计算，改善适配效果

lib/components/gallery_list_normal_card.dart

@@ -49,7 +49,7 @@ class _GalleryListNormalCard extends State<GalleryListNormalCard> {
         : Container();
     final mainWidget = Padding(
         padding: useMobile
-            ? const EdgeInsets.symmetric(vertical: 2, horizontal: 4)
+            ? EdgeInsets.symmetric(vertical: 2 / dpr, horizontal: 4 / dpr)
             : EdgeInsets.all(8 / dpr),
         child: Column(crossAxisAlignment: CrossAxisAlignment.center, children: [
           SelectableText(

lib/components/thumbnail.dart

@@ -311,8 +311,8 @@ class _Thumbnail extends State<Thumbnail> {
             child: timg)
         : timg;
     return SizedBox(
-        width: widget.width * dpr,
-        height: widget.height * dpr,
+        width: widget.width / dpr,
+        height: widget.height / dpr,
         child: isLoading
             ? const Center(child: CircularProgressIndicator())
             : _data != null