style: 优化为黑金/白金配色方案

- 暗色主题: 黑金传奇 (深黑 + 真金)
- 亮色主题: 白金殿堂 (纯白 + 金色)
- 统一品牌色: 金色强调
- 提升专业金融感

flutter_monisuo/lib/ui/components/neon_glow.dart

@@ -259,31 +259,8 @@ class _NeonButtonState extends State<NeonButton>
   }
 
   LinearGradient? get _gradient {
-    if (widget.type == NeonButtonType.outline) return null;
-
-    final isDark = Theme.of(context).brightness == Brightness.dark;
-    final colorScheme = Theme.of(context).colorScheme;
-
-    switch (widget.type) {
-      case NeonButtonType.primary:
-        return LinearGradient(
-          colors: [colorScheme.primary, colorScheme.primaryContainer],
-          begin: const Alignment(-0.7, -0.7),
-          end: const Alignment(0.7, 0.7),
-        );
-      case NeonButtonType.secondary:
-        return LinearGradient(
-          colors: [colorScheme.secondary, colorScheme.secondaryContainer ?? colorScheme.secondary],
-          begin: const Alignment(-0.7, -0.7),
-          end: const Alignment(0.7, 0.7),
-        );
-      case NeonButtonType.tertiary:
-        return AppColorScheme.getBuyGradient(isDark);
-      case NeonButtonType.error:
-        return AppColorScheme.sellGradient;
-      default:
-        return null;
-    }
+    // 【优化】移除所有渐变效果，改为纯色背景，提升专业金融感
+    return null;
   }
 
   @override