feat: 数据集版本管理

新增数据集版本创建、切换、激活与历史追溯能力，Mock 通过 localStorage 持久化版本状态并接入版本接口路由，预览页支持版本对比与内容回滚，列表补充版本入口，回归脚本扩充断言。

frontend/src/api/modules/dataset.ts

@@ -1,5 +1,5 @@
 import { get, post, put, del } from '../request'
-import type { DatasetItem } from '@/types'
+import type { DatasetItem, DatasetVersion, DatasetVersionList } from '@/types'
 
 /** 数据集列表 */
 export const getDatasetList = () => get<DatasetItem[]>('/dataset-manage')
@@ -29,11 +29,58 @@ export const uploadDatasetFiles = (datasetId: string | number, files: File[]) =>
 
 /** 预览数据集文件内容 */
 export const previewDatasetFile = (fileId: string | number) =>
-  get<{ content: string }>(`/dataset-manage/preview/${fileId}`)
+  get<{ content: string }>(`/dataset-manage/preview/${encodeURIComponent(fileId)}`)
+
+/** 数据集文件版本列表 */
+export const getDatasetFileVersions = (fileId: string | number) =>
+  get<DatasetVersionList>(`/dataset-manage/versions/${encodeURIComponent(fileId)}`)
+
+/** 读取指定历史版本内容（不改变当前版本） */
+export const getDatasetFileVersionContent = (fileId: string | number, versionId: string) =>
+  get<{ version: DatasetVersion; content: string }>(
+    `/dataset-manage/versions/${encodeURIComponent(fileId)}/${encodeURIComponent(versionId)}`,
+  )
+
+/** 保存为新版本，并自动设为当前版本 */
+export const createDatasetFileVersion = (
+  fileId: string | number,
+  content: string,
+  options: {
+    description?: string
+    baseVersionId: string
+    expectedCurrentVersionId: string
+  },
+) =>
+  post<{ version: DatasetVersion; content: string }>(
+    `/dataset-manage/versions/${encodeURIComponent(fileId)}`,
+    {
+      content,
+      description: options.description || '在线编辑',
+      base_version_id: options.baseVersionId,
+      expected_current_version_id: options.expectedCurrentVersionId,
+    },
+  )
+
+/** 切换当前使用的数据集版本 */
+export const activateDatasetFileVersion = (
+  fileId: string | number,
+  versionId: string,
+  expectedCurrentVersionId: string,
+) =>
+  put<{ version: DatasetVersion; content: string }>(
+    `/dataset-manage/versions/${encodeURIComponent(fileId)}/active`,
+    { version_id: versionId, expected_current_version_id: expectedCurrentVersionId },
+  )
 
 /** 下载文件 URL */
-export const downloadFileUrl = (datasetId: string | number, fileId: string | number) =>
-  `/api/dataset-manage/download/${datasetId}/${fileId}`
+export const downloadFileUrl = (
+  datasetId: string | number,
+  fileId: string | number,
+  versionId?: string,
+) => {
+  const baseUrl = `/api/dataset-manage/download/${datasetId}/${fileId}`
+  return versionId ? `${baseUrl}?version_id=${encodeURIComponent(versionId)}` : baseUrl
+}
 
 /** 打包下载数据集 URL */
 export const downloadDatasetUrl = (datasetId: string | number) =>