feat(i18n): add document processing confirmation dialog translations

- Add "processingDocuments" translation key for loading state message in English and Chinese
- Add "startUploadConfirmTitle" translation for confirmation dialog title
- Add "startUploadConfirmContent" translation for confirmation dialog description
- Add "returnToList" translation for returning to list page action
- Add "stayOnPage" translation for staying on current page action
- Support user choice to either return to list or stay on page during background document processing

web/src/i18n/zh.ts

@@ -183,6 +183,7 @@ export const zh = {
       fileName: '文件名称',
       fileList: '文件列表',
       blockPreview: '分块预览',
+      processingDocuments: '正在处理文档，请稍候...',
       chunkContent: '分块内容',
       sampleChunk: '示例分块内容',
       noFilesSelected: '暂无文件',
@@ -192,6 +193,10 @@ export const zh = {
       waiting: '等待中',
       startUpload: '共{{count}}个文件 | 开始上传',
       startUploading: '开始上传',
+      startUploadConfirmTitle: '开始处理文档',
+      startUploadConfirmContent: '文档处理将在后台进行，您可以选择立即返回列表页或停留在此页面查看处理进度。',
+      returnToList: '返回列表页',
+      stayOnPage: '停留在此页',
       uploadSuccess: '上传成功',
       datasetName: '数据集名称',
       pleaseEnterDatasetName: '请输入数据集名称',