style(UploadVideoPopup): 更新进度条样式并清除上传结果

更新进度条的颜色和渐变样式以提升视觉效果。在上传新文件前清除之前的上传结果，确保用户界面的一致性。

@@ -26,7 +26,7 @@
         </van-uploader>
 
         <div v-if="uploadProgress > 0 && uploadProgress < 100" class="progress">
-          <van-progress :percentage="uploadProgress" :show-pivot="true" />
+          <van-progress :percentage="uploadProgress" :show-pivot="true" pivot-color="#7232dd" color="linear-gradient(to right, #be99ff, #7232dd)" />
         </div>
 
         <div v-if="videoUrl" class="video-preview">
@@ -84,6 +84,12 @@ const beforeRead = (file) => {
 };
 
 const afterRead = async (file) => {
+  // 清除之前的上传结果
+  videoUrl.value = '';
+  videoId.value = '';
+  videoName.value = '';
+  uploadProgress.value = 0;
+
   const formData = new FormData();
   formData.append('file', file.file);