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>

backend/src/common/services/activity.service.ts

@@ -290,6 +290,113 @@ export const activityService = {
     };
   },
 
+  /**
+   * 分页查询运营日志（支持筛选）
+   * 
+   * @param options 查询选项
+   */
+  async getActivityLogs(options: {
+    page: number;
+    pageSize: number;
+    startDate?: Date;
+    endDate?: Date;
+    module?: string;
+    action?: string;
+    keyword?: string;
+  }): Promise<{
+    data: Array<{
+      id: string;
+      createdAt: Date;
+      tenantId: string;
+      tenantName: string | null;
+      userId: string;
+      userName: string | null;
+      module: string;
+      feature: string;
+      action: string;
+      info: string | null;
+    }>;
+    total: number;
+    page: number;
+    pageSize: number;
+  }> {
+    const { page, pageSize, startDate, endDate, module, action, keyword } = options;
+    
+    // 构建 where 条件
+    const where: any = {};
+    
+    // 日期范围筛选
+    if (startDate || endDate) {
+      where.created_at = {};
+      if (startDate) where.created_at.gte = startDate;
+      if (endDate) {
+        // endDate 设置到当天结束
+        const endOfDay = new Date(endDate);
+        endOfDay.setHours(23, 59, 59, 999);
+        where.created_at.lte = endOfDay;
+      }
+    }
+    
+    // 模块筛选
+    if (module) {
+      where.module = module;
+    }
+    
+    // 动作筛选
+    if (action) {
+      where.action = action;
+    }
+    
+    // 关键词搜索（用户名或租户名）
+    if (keyword) {
+      where.OR = [
+        { user_name: { contains: keyword, mode: 'insensitive' } },
+        { tenant_name: { contains: keyword, mode: 'insensitive' } },
+      ];
+    }
+    
+    // 并行查询数据和总数
+    const [logs, total] = await Promise.all([
+      prisma.simple_logs.findMany({
+        where,
+        orderBy: { created_at: 'desc' },
+        skip: (page - 1) * pageSize,
+        take: pageSize,
+        select: {
+          id: true,
+          created_at: true,
+          tenant_id: true,
+          tenant_name: true,
+          user_id: true,
+          user_name: true,
+          module: true,
+          feature: true,
+          action: true,
+          info: true,
+        }
+      }),
+      prisma.simple_logs.count({ where }),
+    ]);
+    
+    return {
+      data: logs.map(log => ({
+        id: log.id,
+        createdAt: log.created_at,
+        tenantId: log.tenant_id,
+        tenantName: log.tenant_name,
+        userId: log.user_id,
+        userName: log.user_name,
+        module: log.module,
+        feature: log.feature,
+        action: log.action,
+        info: log.info,
+      })),
+      total,
+      page,
+      pageSize,
+    };
+  },
+
   /**
    * 清理过期日志（180天前的数据）
    * 用于定时任务调用