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/apps/agent/observability/traffic.go

@@ -22,6 +22,7 @@ type accessLogRecord struct {
 	Host          string  `json:"host"`
 	RemoteAddr    string  `json:"remote_addr"`
 	Path          string  `json:"path"`
+	UserAgent     string  `json:"user_agent"`
 	Status        int     `json:"status"`
 	BytesSent     int64   `json:"bytes_sent"`
 	RequestLength int64   `json:"request_length"`
@@ -145,6 +146,7 @@ func (aggregate *trafficAggregate) consume(line []byte) {
 		RemoteAddr:    strings.TrimSpace(record.RemoteAddr),
 		Host:          strings.TrimSpace(record.Host),
 		Path:          normalizeAccessLogPath(record.Path),
+		UserAgent:     strings.TrimSpace(record.UserAgent),
 		StatusCode:    record.Status,
 		BytesSent:     record.BytesSent,
 		RequestLength: record.RequestLength,
@@ -157,6 +159,7 @@ type parsedAccessLogRecord struct {
 	Host          string
 	RemoteAddr    string
 	Path          string
+	UserAgent     string
 	Status        int
 	BytesSent     int64
 	RequestLength int64
@@ -189,6 +192,7 @@ func parseJSONAccessLogRecord(raw string) (parsedAccessLogRecord, bool) {
 		Host:          strings.TrimSpace(record.Host),
 		RemoteAddr:    strings.TrimSpace(record.RemoteAddr),
 		Path:          normalizeAccessLogPath(record.Path),
+		UserAgent:     strings.TrimSpace(record.UserAgent),
 		Status:        record.Status,
 		BytesSent:     record.BytesSent,
 		RequestLength: record.RequestLength,