fix(traffic): persist delayed-start expiry only for converted clients

addClientTraffic's second pass wrote expiry_time for every polled row via
UPDATE ... WHERE expiry_time < 0 — a no-op statement per active client on
every 5s poll, since almost all rows carry a positive expiry. At 10k
active clients that was 10k pointless indexed UPDATEs per poll.

adjustTraffics now returns the emails it actually converted this tick and
the persistence pass writes exactly those, in sorted order to keep
concurrent writers lock-compatible on Postgres. Behavior is unchanged:
unconverted rows never matched the WHERE clause anyway.

internal/web/service/inbound_traffic.go

@@ -5,6 +5,8 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"maps"
+	"slices"
 	"strings"
 	"time"
 
@@ -125,7 +127,7 @@ func (s *InboundService) addClientTraffic(tx *gorm.DB, traffics []*xray.ClientTr
 		return nil
 	}
 
-	dbClientTraffics, err = s.adjustTraffics(tx, dbClientTraffics)
+	dbClientTraffics, convertedExpiryByEmail, err := s.adjustTraffics(tx, dbClientTraffics)
 	if err != nil {
 		return err
 	}
@@ -161,22 +163,22 @@ func (s *InboundService) addClientTraffic(tx *gorm.DB, traffics []*xray.ClientTr
 
 	// adjustTraffics converts delayed-start rows (negative ExpiryTime → absolute
 	// deadline) in-memory. Persist that conversion now since the traffic UPDATE
-	// above only touches up/down/last_online.
-	for _, ct := range dbClientTraffics {
-		if ct.ExpiryTime > 0 {
-			if err = tx.Exec(
-				`UPDATE client_traffics SET expiry_time = ? WHERE email = ? AND expiry_time < 0`,
-				ct.ExpiryTime, ct.Email,
-			).Error; err != nil {
-				logger.Warning("AddClientTraffic update expiry_time ", err)
-			}
+	// above only touches up/down/last_online. Only converted emails are written:
+	// updating every polled row issued one no-op UPDATE per active client per
+	// poll. Sorted order keeps concurrent writers lock-compatible on Postgres.
+	for _, email := range slices.Sorted(maps.Keys(convertedExpiryByEmail)) {
+		if err = tx.Exec(
+			`UPDATE client_traffics SET expiry_time = ? WHERE email = ? AND expiry_time < 0`,
+			convertedExpiryByEmail[email], email,
+		).Error; err != nil {
+			logger.Warning("AddClientTraffic update expiry_time ", err)
 		}
 	}
 
 	return nil
 }
 
-func (s *InboundService) adjustTraffics(tx *gorm.DB, dbClientTraffics []*xray.ClientTraffic) ([]*xray.ClientTraffic, error) {
+func (s *InboundService) adjustTraffics(tx *gorm.DB, dbClientTraffics []*xray.ClientTraffic) ([]*xray.ClientTraffic, map[string]int64, error) {
 	now := time.Now().UnixMilli()
 
 	// "Start After First Use" stores a negative expiry (the duration). On the
@@ -190,7 +192,7 @@ func (s *InboundService) adjustTraffics(tx *gorm.DB, dbClientTraffics []*xray.Cl
 		}
 	}
 	if len(newExpiryByEmail) == 0 {
-		return dbClientTraffics, nil
+		return dbClientTraffics, nil, nil
 	}
 
 	delayedEmails := make([]string, 0, len(newExpiryByEmail))
@@ -208,16 +210,16 @@ func (s *InboundService) adjustTraffics(tx *gorm.DB, dbClientTraffics []*xray.Cl
 		Distinct().
 		Pluck("client_inbounds.inbound_id", &inboundIds).Error
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 	if len(inboundIds) == 0 {
-		return dbClientTraffics, nil
+		return dbClientTraffics, nil, nil
 	}
 
 	var inbounds []*model.Inbound
 	err = tx.Model(model.Inbound{}).Where("id IN (?)", inboundIds).Find(&inbounds).Error
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 	for inbound_index := range inbounds {
 		settings := map[string]any{}
@@ -243,7 +245,7 @@ func (s *InboundService) adjustTraffics(tx *gorm.DB, dbClientTraffics []*xray.Cl
 			settings["clients"] = newClients
 			modifiedSettings, err := json.MarshalIndent(settings, "", "  ")
 			if err != nil {
-				return nil, err
+				return nil, nil, err
 			}
 
 			inbounds[inbound_index].Settings = string(modifiedSettings)
@@ -276,7 +278,7 @@ func (s *InboundService) adjustTraffics(tx *gorm.DB, dbClientTraffics []*xray.Cl
 		}
 	}
 
-	return dbClientTraffics, nil
+	return dbClientTraffics, newExpiryByEmail, nil
 }
 
 func (s *InboundService) autoRenewClients(tx *gorm.DB) (bool, int64, error) {