feat(frontend): add loading state to publish button to prevent duplicate clicks

- Add publishing state property to each tab to track publishing status
- Implement loading indicator on publish button with visual feedback
- Prevent duplicate clicks during active publishing process
- Update button text to show "发布中..." (Publishing...) when loading
- Ensure publishing state is properly reset in all scenarios (success, failure, validation errors)
- Add duplicate click prevention with user-friendly error message

The publish button now shows a loading spinner and prevents multiple clicks
during the publishing process, improving user experience and preventing
duplicate uploads to social media platforms.

sau_frontend/src/views/PublishCenter.vue

@@ -457,7 +457,14 @@
           <!-- 操作按钮 -->
           <div class="action-buttons">
             <el-button size="small" @click="cancelPublish(tab)">取消</el-button>
-            <el-button size="small" type="primary" @click="confirmPublish(tab)">发布</el-button>
+            <el-button
+              size="small"
+              type="primary"
+              @click="confirmPublish(tab)"
+              :loading="tab.publishing || false"
+            >
+              {{ tab.publishing ? '发布中...' : '发布' }}
+            </el-button>
           </div>
         </div>
       </div>
@@ -526,7 +533,8 @@ const defaultTabInit = {
   videosPerDay: 1, // 每天发布视频数量
   dailyTimes: ['10:00'], // 每天发布时间点列表
   startDays: 0, // 从今天开始计算的发布天数，0表示明天，1表示后天
-  publishStatus: null // 发布状态，包含message和type
+  publishStatus: null, // 发布状态，包含message和type
+  publishing: false // 发布状态，用于控制按钮loading效果
 }
 
 // helper to create a fresh deep-copied tab from defaultTabInit
@@ -733,25 +741,36 @@ const cancelPublish = (tab) => {
 
 // 确认发布
 const confirmPublish = async (tab) => {
+  // 防止重复点击
+  if (tab.publishing) {
+    return Promise.reject(new Error('正在发布中，请稍候...'))
+  }
+
+  tab.publishing = true // 设置发布状态为进行中
+
   return new Promise((resolve, reject) => {
     // 数据验证
     if (tab.fileList.length === 0) {
       ElMessage.error('请先上传视频文件')
+      tab.publishing = false // 重置发布状态
       reject(new Error('请先上传视频文件'))
       return
     }
     if (!tab.title.trim()) {
       ElMessage.error('请输入标题')
+      tab.publishing = false // 重置发布状态
       reject(new Error('请输入标题'))
       return
     }
     if (!tab.selectedPlatform) {
       ElMessage.error('请选择发布平台')
+      tab.publishing = false // 重置发布状态
       reject(new Error('请选择发布平台'))
       return
     }
     if (tab.selectedAccounts.length === 0) {
       ElMessage.error('请选择发布账号')
+      tab.publishing = false // 重置发布状态
       reject(new Error('请选择发布账号'))
       return
     }
@@ -815,6 +834,9 @@ const confirmPublish = async (tab) => {
       }
       reject(error)
     })
+    .finally(() => {
+      tab.publishing = false // 重置发布状态
+    })
   })
 }