refactor(TaskView): 调整任务列表展示逻辑

-移除任务列表中的"送达率"列
- 更新"已发/成功/总数"列的显示格式，移除"送达"数据
- 根据用户权限动态显示"送达率"列

src/views/TaskView.vue

@@ -172,14 +172,13 @@
                 <ElTag v-else>未知</ElTag>
             </template>
         </ElTableColumn>
-        <ElTableColumn prop="sent" label="已发/成功/送达/总数" align="center" width="180">
+        <ElTableColumn prop="sent" label="已发/成功/总数" align="center" width="180">
             <template #default="{ row }">
-                {{ row.sent || 0 }} / {{ row.successCount }}/ {{ row.deliveryCount || 0 }} /
-                {{ row.total || 0 }}
+                {{ row.sent || 0 }} / {{ row.successCount }} / {{ row.total || 0 }}
             </template>
         </ElTableColumn>
         <ElTableColumn prop="successRate" label="成功率" align="center" width="80" />
-        <ElTableColumn prop="deliveryRate" label="送达率" align="center" width="80" />
+        <ElTableColumn prop="deliveryRate" v-if="isAdmin" label="送达率" align="center" width="80" />
         <ElTableColumn prop="createdAt" label="创建时间" :formatter="timeFormatter" width="100" />
         <ElTableColumn prop="startedAt" label="开始时间" :formatter="startedTimeFormatter" width="100" />
         <ElTableColumn prop="updatedAt" label="结束时间" :formatter="updatedTimeFormatter" width="100" />