feat: 支持FAQ Excel导入导出并优化管理端交互

- 新增 FAQ Excel 导入、导出、模板下载接口及导入结果 VO，支持按分类路径+问题 upsert 与逐行容错

- 模板增加填写说明与更宽列宽，导出列与模板保持一致

- 管理端新增导入弹窗与结果展示，FAQ 列表操作栏精简为"添加 + 更多操作"并去除多余外层框

- 修复导出前校验顺序，避免非 FAQ 知识库触发默认分类写入

easyflow-ui-admin/app/src/locales/langs/en-US/documentCollection.json

@@ -112,7 +112,23 @@
     "collectionRequired": "Collection id is required",
     "imageTypeInvalid": "Only JPG/PNG/WEBP/GIF images are supported",
     "imageSizeExceeded": "Image size must be less than 5MB",
-    "imageUploadFailed": "Image upload failed"
+    "imageUploadFailed": "Image upload failed",
+    "import": {
+      "title": "Import FAQ",
+    "uploadTitle": "Drop Excel file here or click to upload",
+    "uploadDesc": "Only .xlsx/.xls files are supported, max 5000 rows in first sheet",
+    "moreActions": "More Actions",
+    "downloadTemplate": "Download Template",
+      "startImport": "Start Import",
+      "importFinished": "Import completed",
+      "resultTitle": "Import Result",
+      "totalCount": "Total",
+      "successCount": "Success",
+      "errorCount": "Failed",
+      "rowNumber": "Row",
+      "reason": "Reason",
+      "selectFileRequired": "Please select an Excel file first"
+    }
   },
   "searchResults": "SearchResults",
   "documentPreview": "DocumentPreview",

easyflow-ui-admin/app/src/locales/langs/zh-CN/documentCollection.json

@@ -112,7 +112,23 @@
     "collectionRequired": "知识库ID不能为空",
     "imageTypeInvalid": "仅支持 JPG/PNG/WEBP/GIF 图片",
     "imageSizeExceeded": "图片大小不能超过5MB",
-    "imageUploadFailed": "图片上传失败"
+    "imageUploadFailed": "图片上传失败",
+    "import": {
+      "title": "导入FAQ",
+    "uploadTitle": "将 Excel 文件拖拽到此处，或点击上传",
+    "uploadDesc": "仅支持 .xlsx/.xls，首个工作表最多5000条",
+    "moreActions": "更多操作",
+    "downloadTemplate": "下载导入模板",
+      "startImport": "开始导入",
+      "importFinished": "导入完成",
+      "resultTitle": "导入结果",
+      "totalCount": "总数",
+      "successCount": "成功数",
+      "errorCount": "失败数",
+      "rowNumber": "行号",
+      "reason": "失败原因",
+      "selectFileRequired": "请先选择Excel文件"
+    }
   },
   "searchResults": "检索结果",
   "documentPreview": "文档预览",