feat: 支持知识库 CSV 大文件导入

- 增加 CSV 流式解析、表格语义分块和分页预览

- 增加快照两阶段清理、失败重试和格式校验

- 补充批量入口、管理端交互和回归测试

easyflow-ui-admin/app/src/views/ai/documentCollection/ImportKnowledgeFileContainer.vue

@@ -81,6 +81,7 @@ const MAX_FILE_COUNT = 2000;
 const MAX_FILE_SIZE_BYTES = 100 * 1024 * 1024;
 const MAX_TOTAL_SIZE_BYTES = 1024 * 1024 * 1024;
 const SUPPORTED_EXTENSIONS = new Set([
+  'csv',
   'docx',
   'md',
   'pdf',
@@ -537,7 +538,7 @@ async function createClientFileKey(relativePath: string) {
         class="native-file-input"
         type="file"
         multiple
-        accept=".txt,.pdf,.docx,.md,.pptx,.xlsx"
+        accept=".txt,.pdf,.docx,.md,.pptx,.xlsx,.csv"
         @change="handleNativeSelection"
       />
       <input