feat(obs): 访问日志 SSOT 与 edge_health，去掉协议兼容层

Agent 仅上报 host_metrics/edge_health/access_logs；业务流量与 UV 由
Server 侧访问日志聚合。新增 of_node_edge_health 与 of_access_log_hourly，
删除 request_reports/openresty 吞吐路径；API 不再暴露 traffic_reports
与 openresty_rx|tx。心跳/离线默认阈值与回填迁移一并入库。

internal/apps/openflare/observability/access_log_logics.go

@@ -16,6 +16,7 @@ const (
 	maxAccessLogPageSize       = 200
 	defaultAccessLogSortBy     = "logged_at"
 	defaultAccessLogSortOrder  = "desc"
+	accessLogSortOrderAsc      = "asc"
 	defaultAccessLogFoldMinute = 3
 	defaultIPTrendHours        = 24
 	defaultIPTrendBucketMinute = 30
@@ -605,8 +606,8 @@ func normalizeAccessLogSortBy(sortBy string) string {
 }
 
 func normalizeAccessLogSortOrder(sortOrder string) string {
-	if strings.EqualFold(strings.TrimSpace(sortOrder), "asc") {
-		return "asc"
+	if strings.EqualFold(strings.TrimSpace(sortOrder), accessLogSortOrderAsc) {
+		return accessLogSortOrderAsc
 	}
 	return defaultAccessLogSortOrder
 }