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

internal/model/openflare_access_log_store.go

@@ -284,6 +284,7 @@ func toAnalyticsNodeAccessLog(record *OpenFlareAccessLog) analyticsmodel.NodeAcc
 		Region:        record.Region,
 		Host:          record.Host,
 		Path:          record.Path,
+		UserAgent:     record.UserAgent,
 		StatusCode:    openFlareAccessLogStatusCodeToInt32(record.StatusCode),
 		BytesSent:     bytesSent,
 		RequestLength: requestLength,
@@ -315,6 +316,7 @@ func fromAnalyticsNodeAccessLogs(rows []analyticsmodel.NodeAccessLog) []*OpenFla
 			Region:        row.Region,
 			Host:          row.Host,
 			Path:          row.Path,
+			UserAgent:     row.UserAgent,
 			StatusCode:    int(row.StatusCode),
 			BytesSent:     bytesSent,
 			RequestLength: requestLength,