feat(access-logs): 接入 User-Agent 与设备/浏览器/状态码分布

- Agent 访问日志上报 user_agent，OpenResty log_format 输出 http_user_agent
- of_node_access_logs 新增 user_agent 列并写入 ClickHouse
- 访问日志概览新增：设备类型饼图、状态码饼图、浏览器/OS/User-Agent 排行
- 日志明细列表增加 User-Agent 列
- 扩展 UA 解析工具（browser/os/device）并支持 CLI 识别

frontend/lib/services/openflare/types.ts

@@ -527,6 +527,11 @@ export interface AccessLogOverview {
   top_paths: DistributionItem[];
   top_hosts: DistributionItem[];
   top_ips: DistributionItem[];
+  device_types: DistributionItem[];
+  top_browsers: DistributionItem[];
+  top_operating_systems: DistributionItem[];
+  top_user_agents: DistributionItem[];
+  status_codes: DistributionItem[];
 }
 
 export interface AccessLogItem {
@@ -538,6 +543,7 @@ export interface AccessLogItem {
   region: string;
   host: string;
   path: string;
+  user_agent: string;
   status_code: number;
 }