fix(ui): 修复主题切换功能，支持明暗主题动态切换

- 替换所有硬编码颜色为动态颜色
- 所有页面使用 Theme.of(context) 获取主题颜色
- 支持深色和浅色主题切换
- 修复 GlassPanel 和 NeonGlow 组件的主题适配
- 完善 lightMaterial ColorScheme 定义
- 测试主题切换功能正常

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

flutter_monisuo/lib/ui/components/gradient_button.dart

@@ -91,7 +91,10 @@ class GradientButton extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final buttonGradient = gradient ?? AppColorScheme.darkCtaGradient;
+    final isDark = Theme.of(context).brightness == Brightness.dark;
+    final colorScheme = Theme.of(context).colorScheme;
+    final buttonGradient = gradient ??
+        (isDark ? AppColorScheme.darkCtaGradient : AppColorScheme.lightCtaGradient);
 
     return Container(
       width: isFullWidth ? double.infinity : null,