feat(admin): Add activity logs page and fix AI chat markdown rendering

- Add paginated activity logs API with filters (date, module, action, keyword)

- Add ActivityLogsPage with table, filters, and detail modal

- Add markdown rendering support for AI chat messages

- Remove prototype placeholder content from chat sidebar

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend-v2/src/pages/admin/api/activityApi.ts

@@ -0,0 +1,73 @@
+/**
+ * 运营日志 API
+ * 
+ * @date 2026-01-28
+ */
+
+import apiClient from '../../../common/api/axios'
+
+// ==================== 类型定义 ====================
+
+export interface ActivityLog {
+  id: string
+  createdAt: string
+  tenantId: string
+  tenantName: string | null
+  userId: string
+  userName: string | null
+  module: string
+  feature: string
+  action: string
+  info: string | null
+}
+
+export interface Pagination {
+  page: number
+  pageSize: number
+  total: number
+  totalPages: number
+}
+
+export interface ActivityLogsResponse {
+  success: boolean
+  data: ActivityLog[]
+  pagination: Pagination
+}
+
+export interface ActivityLogsParams {
+  page?: number
+  pageSize?: number
+  startDate?: string
+  endDate?: string
+  module?: string
+  action?: string
+  keyword?: string
+}
+
+// ==================== API 函数 ====================
+
+/**
+ * 获取运营日志列表（分页）
+ */
+export async function fetchActivityLogs(params: ActivityLogsParams = {}): Promise<{
+  data: ActivityLog[]
+  pagination: Pagination
+}> {
+  const queryParams = new URLSearchParams()
+  
+  if (params.page) queryParams.append('page', String(params.page))
+  if (params.pageSize) queryParams.append('pageSize', String(params.pageSize))
+  if (params.startDate) queryParams.append('startDate', params.startDate)
+  if (params.endDate) queryParams.append('endDate', params.endDate)
+  if (params.module) queryParams.append('module', params.module)
+  if (params.action) queryParams.append('action', params.action)
+  if (params.keyword) queryParams.append('keyword', params.keyword)
+
+  const url = `/api/admin/stats/logs${queryParams.toString() ? '?' + queryParams.toString() : ''}`
+  const res = await apiClient.get<ActivityLogsResponse>(url)
+  
+  return {
+    data: res.data.data,
+    pagination: res.data.pagination,
+  }
+}