refactor(theme): 迁移主题感知颜色至 ThemeExtension

- 创建 AppThemeColors ThemeExtension 类，统一管理主题感知颜色（涨跌色、卡片背景、渐变等）
- 从 AppColorScheme 移除主题感知辅助函数，仅保留静态颜色常量
- 在 AppTheme 中注册 ThemeExtension，支持深色/浅色主题工厂
- 重构所有 UI 组件使用 context.appColors 访问主题颜色，替代硬编码的 AppColorScheme 方法调用
- 移除组件中重复的 isDark 判断逻辑，简化颜色获取方式
- 保持向后兼容性，所有现有功能不变

flutter_monisuo/lib/ui/components/neon_glow.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import '../../core/theme/app_color_scheme.dart';
 import '../../core/theme/app_spacing.dart';
+import '../../core/theme/app_theme_extension.dart';
 
 /// NeonGlow - 霓虹光效组件
 ///
@@ -94,7 +95,7 @@ class NeonGlow extends StatelessWidget {
   }) {
     return NeonGlow(
       key: key,
-      glowColor: AppColorScheme.down.withOpacity(0.3),
+      glowColor: AppColorScheme.down.withValues(alpha: 0.3),
       blurRadius: blurRadius,
       borderRadius: borderRadius,
       child: child,
@@ -205,16 +206,15 @@ class _NeonButtonState extends State<NeonButton>
   }
 
   Color get _backgroundColor {
-    final isDark = Theme.of(context).brightness == Brightness.dark;
-    final colorScheme = Theme.of(context).colorScheme;
+    final colors = context.colors;
 
     switch (widget.type) {
       case NeonButtonType.primary:
-        return colorScheme.primary;
+        return colors.primary;
       case NeonButtonType.secondary:
-        return colorScheme.secondary;
+        return colors.secondary;
       case NeonButtonType.tertiary:
-        return AppColorScheme.getUpColor(isDark);
+        return context.appColors.up;
       case NeonButtonType.error:
         return AppColorScheme.down;
       case NeonButtonType.outline:
@@ -223,38 +223,37 @@ class _NeonButtonState extends State<NeonButton>
   }
 
   Color get _foregroundColor {
-    final isDark = Theme.of(context).brightness == Brightness.dark;
-    final colorScheme = Theme.of(context).colorScheme;
+    final colors = context.colors;
 
     switch (widget.type) {
       case NeonButtonType.primary:
-        return isDark ? AppColorScheme.darkOnPrimary : const Color(0xFFFFFFFF);
+        return colors.onPrimary;
       case NeonButtonType.secondary:
-        return isDark ? AppColorScheme.darkOnSecondary : const Color(0xFFFFFFFF);
+        return colors.onSecondary;
       case NeonButtonType.tertiary:
-        return isDark ? AppColorScheme.darkOnTertiary : const Color(0xFFFFFFFF);
+        return colors.onTertiary;
       case NeonButtonType.error:
         return const Color(0xFFFFFFFF);
       case NeonButtonType.outline:
-        return colorScheme.primary;
+        return colors.primary;
     }
   }
 
   Color get _glowColor {
-    final isDark = Theme.of(context).brightness == Brightness.dark;
-    final colorScheme = Theme.of(context).colorScheme;
+    final colors = context.colors;
+    final appColors = context.appColors;
 
     switch (widget.type) {
       case NeonButtonType.primary:
-        return colorScheme.primary.withOpacity(isDark ? 0.15 : 0.08);
+        return colors.primary.withValues(alpha: appColors.glowOpacity);
       case NeonButtonType.secondary:
-        return colorScheme.secondary.withOpacity(isDark ? 0.15 : 0.08);
+        return colors.secondary.withValues(alpha: appColors.glowOpacity);
       case NeonButtonType.tertiary:
-        return AppColorScheme.getUpBackgroundColor(isDark, opacity: isDark ? 0.2 : 0.1);
+        return context.appColors.upBackground;
       case NeonButtonType.error:
-        return AppColorScheme.down.withOpacity(0.3);
+        return AppColorScheme.down.withValues(alpha: 0.3);
       case NeonButtonType.outline:
-        return colorScheme.primary.withOpacity(isDark ? 0.15 : 0.08);
+        return colors.primary.withValues(alpha: appColors.glowOpacity);
     }
   }
 
@@ -265,8 +264,7 @@ class _NeonButtonState extends State<NeonButton>
 
   @override
   Widget build(BuildContext context) {
-    final colorScheme = Theme.of(context).colorScheme;
-    final isDark = Theme.of(context).brightness == Brightness.dark;
+    final colors = context.colors;
 
     final button = GestureDetector(
       onTapDown: widget.onPressed != null ? _onTapDown : null,
@@ -286,7 +284,7 @@ class _NeonButtonState extends State<NeonButton>
             ),
             border: widget.type == NeonButtonType.outline
                 ? Border.all(
-                    color: colorScheme.outlineVariant.withOpacity(0.3),
+                    color: colors.outlineVariant.withValues(alpha: 0.3),
                   )
                 : null,
           ),