fix: 订场页时间标签显示修复 + 约课页列表刷新修复

- private/index.vue: 时间标签改为单时间+竖线样式，第一行加 margin-top 防止被表头遮挡
- courses/index.vue: 修复切换Tab/日期列表不刷新问题(竞态条件+不清空旧数据+无错误处理)
- .env: 冰场馆URL修正

miniprogram/src/pages/comprehensive/private/index.vue

@@ -50,8 +50,11 @@
             v-for="(slot, si) in grid.time_slots"
             :key="si"
             class="grid-row"
+            :class="{ 'grid-row-first': si === 0 }"
           >
-            <view class="time-label-cell">{{ slot.start }}</view>
+            <view class="time-label-cell">
+              <text class="time-text">{{ slot.start }}</text>
+            </view>
             <view
               v-for="court in grid.courts"
               :key="court.id"
@@ -489,24 +492,38 @@ defineExpose({
   display: flex;
 }
 
+.grid-row-first {
+  margin-top: 20rpx;
+}
+
 .time-label-cell {
   width: 128rpx;
   flex-shrink: 0;
   height: 107rpx;
-  display: flex;
-  align-items: center;
-  justify-content: center;
   background: $bg-color-main;
   border-right: 1rpx solid $border-color;
   border-bottom: 1rpx solid $bg-color-hover;
-  color: $text-color-muted;
-  font-size: 20rpx;
-  font-weight: 700;
   position: sticky;
   left: 0;
   z-index: 5;
 }
 
+.time-text {
+  position: absolute;
+  top: 0;
+  left: 0;
+  right: 0;
+  text-align: center;
+  transform: translateY(-50%);
+  background: $bg-color-main;
+  padding: 0 6rpx;
+  font-size: 20rpx;
+  font-weight: 700;
+  color: $text-color-muted;
+  line-height: 1;
+  z-index: 6;
+}
+
 .grid-cell {
   width: 149rpx;
   flex-shrink: 0;