feat(media): 图片占位改为纯色块并去掉扫光

lib/core/widgets/remote_image.dart

@@ -1,10 +1,10 @@
 // Author: fruit.com.cn
+// 职责：统一网络图片入口，补服务地址，并在加载中/失败时显示纯色占位块。
 
 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;
@@ -32,8 +32,6 @@ class RemoteImage extends StatelessWidget {
     this.width,
     this.height,
     this.fit = BoxFit.cover,
-    this.showFallbackIcon = false,
-    this.fallbackIconKey,
     this.fallbackAspectRatio,
     this.fallbackColor = AppColors.raised,
     this.fallbackWidget,
@@ -45,12 +43,10 @@ class RemoteImage extends StatelessWidget {
   final double? width;
   final double? height;
   final BoxFit fit;
-  final bool showFallbackIcon;
-  final Key? fallbackIconKey;
   final double? fallbackAspectRatio;
   final Color fallbackColor;
 
-  /// 自定义兜底：地址为空、加载中、加载失败时都显示它（优先于 [fallbackColor]）。
+  /// 自定义占位：地址为空、加载中、加载失败时都显示它（优先于 [fallbackColor]）。
   final Widget? fallbackWidget;
   final int? decodeWidth;
   final int? decodeHeight;
@@ -58,7 +54,7 @@ class RemoteImage extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final url = AppConfig.mediaUrl(path);
-    if (url.isEmpty) return _fallback(brand: showFallbackIcon);
+    if (url.isEmpty) return _fallback();
     return LayoutBuilder(
       builder: (context, constraints) {
         final pixelRatio = MediaQuery.devicePixelRatioOf(context);
@@ -100,51 +96,23 @@ class RemoteImage extends StatelessWidget {
               ?.clamp(_minImageDecodePixels, _maxImageDecodePixels)
               .toInt(),
           gaplessPlayback: true,
-          errorBuilder: (_, _, _) => _fallback(brand: showFallbackIcon),
+          errorBuilder: (_, _, _) => _fallback(),
           frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
             if (wasSynchronouslyLoaded || frame != null) return child;
-            return _loadingFallback();
+            return _fallback();
           },
         );
       },
     );
   }
 
-  Widget _loadingFallback() {
+  Widget _fallback() {
     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;
-    final mark = brand
-        ? LayoutBuilder(
-            builder: (context, constraints) {
-              final width = constraints.maxWidth.isFinite
-                  ? constraints.maxWidth
-                  : 120.0;
-              return Center(
-                child: Image.asset(
-                  'assets/icon/splash_logo.png',
-                  key: fallbackIconKey,
-                  width: width * 0.72,
-                  fit: BoxFit.contain,
-                ),
-              );
-            },
-          )
-        : null;
-    final fallback = Container(
-      width: width,
-      height: height,
-      color: brand ? AppColors.mediaBlack : fallbackColor,
-      alignment: Alignment.center,
-      child: mark,
-    );
+    final content = custom != null
+        ? SizedBox(width: width, height: height, child: custom)
+        : Container(width: width, height: height, color: fallbackColor);
     final ratio = fallbackAspectRatio;
-    if (ratio == null) return fallback;
-    return AspectRatio(aspectRatio: ratio, child: fallback);
+    if (ratio == null) return content;
+    return AspectRatio(aspectRatio: ratio, child: content);
   }
 }