fix: 修复P2和P3问题

1. P2: 修复订单管理this.$set不兼容Vue3问题，改为直接赋值
2. P3: 修复选手年龄显示-1问题，改为显示"--"

🤖 Generated with Claude Code

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

src/views/martial/order/index.vue

@@ -181,13 +181,13 @@ export default {
         try {
           const res = await getScheduleResult(competition.id)
           if (res.data?.data) {
-            this.$set(this.scheduleStatusMap, competition.id, res.data.data.isCompleted || false)
+            this.scheduleStatusMap[competition.id] = res.data.data.isCompleted || false
           } else {
-            this.$set(this.scheduleStatusMap, competition.id, false)
+            this.scheduleStatusMap[competition.id] = false
           }
         } catch (err) {
           // 如果获取失败，默认为未完成
-          this.$set(this.scheduleStatusMap, competition.id, false)
+          this.scheduleStatusMap[competition.id] = false
         }
       }
     },

src/views/martial/participant/index.vue

@@ -94,11 +94,14 @@
           </el-table-column>
 
           <el-table-column
-            prop="age"
             label="年龄"
             width="80"
             align="center"
-          />
+          >
+            <template #default="scope">
+              {{ scope.row.age === -1 || scope.row.age === null || scope.row.age === undefined ? '--' : scope.row.age }}
+            </template>
+          </el-table-column>
 
           <el-table-column
             prop="organization"