fix(asset): 冻结积分值为0时状态显示为"无"而非"挂单中"

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/mining-app/lib/presentation/pages/asset/asset_page.dart

@@ -839,7 +839,7 @@ class _AssetPageState extends ConsumerState<AssetPage> {
           balance: asset?.frozenCash,
           isLoading: isLoading,
           unit: '积分值',
-          status: '挂单中',
+          status: (double.tryParse(asset?.frozenCash ?? '0') ?? 0) > 0 ? '挂单中' : '无',
           statusColor: AppColors.textMutedOf(context),
           statusBgColor: AppColors.cardOf(context),
           statusBorder: true,