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/repository/analytics/node_observability.go

@@ -159,6 +159,7 @@ ORDER BY %s`, tableName, clause, nodeObservabilityCapturedAtOrderClause())
 	return scanNodeObsFrpcRows(rows)
 }
 
+//nolint:dupl // scan shapes differ by model fields; shared helper would obscure CH column mapping
 func scanNodeMetricSnapshotRows(rows driver.Rows) ([]analyticsmodel.NodeMetricSnapshot, error) {
 	var result []analyticsmodel.NodeMetricSnapshot
 	for rows.Next() {