feat(image): 图片加载占位改为微光骨架

lib/core/widgets/remote_image.dart

@@ -4,6 +4,7 @@ import 'package:flutter/material.dart';
 
 import '../config/app_config.dart';
 import '../theme/app_colors.dart';
+import 'image_placeholder_shimmer.dart';
 
 const int _minImageDecodePixels = 96;
 const int _maxImageDecodePixels = 2048;
@@ -102,13 +103,19 @@ class RemoteImage extends StatelessWidget {
           errorBuilder: (_, _, _) => _fallback(brand: showFallbackIcon),
           frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
             if (wasSynchronouslyLoaded || frame != null) return child;
-            return _fallback(brand: showFallbackIcon);
+            return _loadingFallback();
           },
         );
       },
     );
   }
 
+  Widget _loadingFallback() {
+    final custom = fallbackWidget;
+    if (custom != null) return custom;
+    return ImagePlaceholderShimmer(child: _fallback(brand: showFallbackIcon));
+  }
+
   Widget _fallback({required bool brand}) {
     final custom = fallbackWidget;
     if (custom != null) return custom;