feat(kling): add validation error display in timeline panel and update UI components

- Remove unused audio base64 reference and error message in VoiceSelector
- Rename CSS class from 'result-banner' to 'result-inline' and update button styling
- Pass validationError prop from GenerateStep to TimelinePanel
- Add validation error display in TimelinePanel with error state styling
- Update conditional rendering to show either validation error or duration diff
- Add CloseCircleOutlined icon for error status display

frontend/app/web-gold/src/views/system/task-management/digital-human-task/index.vue

@@ -101,7 +101,7 @@
                   type="link"
                   size="small"
                   class="action-btn action-btn--primary"
-                  @click="handlePreview(record)"
+                  @click="openVideoUrl(record)"
                 >
                   <PlayCircleOutlined /> 预览
                 </a-button>
@@ -111,7 +111,7 @@
                   type="link"
                   size="small"
                   class="action-btn action-btn--success"
-                  @click="handleDownload(record)"
+                  @click="openVideoUrl(record)"
                 >
                   <DownloadOutlined /> 下载
                 </a-button>
@@ -170,17 +170,8 @@ const rowSelection = {
 // 状态判断
 const isStatus = (status, target) => status === target || status === target.toUpperCase()
 
-// 预览视频（直接打开链接）
-const handlePreview = (record) => {
-  if (!record.resultVideoUrl) {
-    message.warning('该任务暂无视频结果，请稍后再试')
-    return
-  }
-  window.open(record.resultVideoUrl, '_blank')
-}
-
-// 下载视频
-const handleDownload = (record) => {
+// 打开视频链接（预览/下载共用）
+const openVideoUrl = (record) => {
   if (!record.resultVideoUrl) {
     message.warning('该任务暂无视频结果，请稍后再试')
     return