fix(today)：站立时长

@@ -132,12 +132,8 @@ class TodayActivityCard extends StatelessWidget {
         // stand 单位为秒，转换为小时+分钟
         List<_MetricValueSpan> standSpans;
         if (stand > 0 && (activityTarget?.stand ?? 0) > 0) {
-          final stHours = stand ~/ 3600;
-          final stMinutes = (stand % 3600) ~/ 60;
           standSpans = [
-            if (stHours > 0) _MetricValueSpan('$stHours', '小时'),
-            if (stMinutes > 0 || stHours == 0)
-              _MetricValueSpan(stMinutes > 0 ? '$stMinutes' : '0', '分钟'),
+            _MetricValueSpan('$stand', '小时'),
           ];
         } else {
           standSpans = [_MetricValueSpan('--', '小时')];