fix(ui): 修复多个UI样式问题

1. 修复 Light Mode 卡片背景色（surfaceCard: #FFFFFF）
2. 修复首页充值按钮颜色（使用主色实心背景+白色文字）
3. 修复'更多'和'资产详情'文字颜色（使用 text-muted）
4. 修复邀请码卡片背景色（使用琥珀色渐变）
5. 修复'复制邀请码'按钮文字颜色（使用 onPrimary）

flutter_monisuo/lib/ui/pages/home/home_page.dart

@@ -544,19 +544,18 @@ class _AssetCardState extends State<_AssetCard> {
                     vertical: AppSpacing.xs + 2,
                   ),
                   decoration: BoxDecoration(
-                    color: context.colors.primary.withValues(alpha: 0.1),
+                    color: context.colors.primary,
                     borderRadius: BorderRadius.circular(AppRadius.full),
-                    border: Border.all(color: context.colors.primary.withValues(alpha: 0.2)),
                   ),
                   child: Row(
                     mainAxisSize: MainAxisSize.min,
                     children: [
-                      Icon(Icons.add, size: 14, color: context.colors.primary),
+                      Icon(Icons.add, size: 14, color: context.colors.onPrimary),
                       SizedBox(width: AppSpacing.xs),
                       Text(
                         '充值',
                         style: AppTextStyles.labelLarge(context).copyWith(
-                          color: context.colors.primary,
+                          color: context.colors.onPrimary,
                         ),
                       ),
                     ],
@@ -957,7 +956,7 @@ class _HoldingsSection extends StatelessWidget {
             TextButton(
               onPressed: () {},
               style: TextButton.styleFrom(
-                foregroundColor: context.colors.primary,
+                foregroundColor: context.appColors.onSurfaceMuted,
                 padding: const EdgeInsets.symmetric(horizontal: AppSpacing.sm),
               ),
               child: Row(
@@ -968,7 +967,7 @@ class _HoldingsSection extends StatelessWidget {
                       )),
                   const SizedBox(width: AppSpacing.xs),
                   Icon(LucideIcons.chevronRight,
-                      size: 16, color: context.colors.primary),
+                      size: 16, color: context.appColors.onSurfaceMuted),
                 ],
               ),
             ),

flutter_monisuo/lib/ui/pages/home/hot_coins_section.dart

@@ -24,7 +24,9 @@ class HotCoinsSection extends StatelessWidget {
               ),
               Text(
                 '更多',
-                style: AppTextStyles.bodyMedium(context),
+                style: AppTextStyles.bodyMedium(context).copyWith(
+                  color: context.appColors.onSurfaceMuted,
+                ),
               ),
             ],
           ),