fix(client): honor keepTraffic when deleting a client that is attached to inbounds

Delete, DeleteByEmail and BulkDelete all pass keepTraffic to their final
cleanup transaction, but each called the per-inbound delete helper with a
hardcoded false. That helper purges the client's traffic, IP and stat rows
before the gated cleanup runs, so keepTraffic=true still destroyed all
traffic history for any client actually attached to an inbound (the pinned
test only covered a record with no inbound mappings). Thread the caller's
keepTraffic through to the per-inbound helper at all three call sites.

internal/web/service/bulk_traffic_test.go

@@ -119,6 +119,33 @@ func TestDelDepletedRemovesOnlyDepleted(t *testing.T) {
 	}
 }
 
+func TestClientDeleteKeepTrafficPreservesRowForAttachedClient(t *testing.T) {
+	setupBulkDB(t)
+	svc := &ClientService{}
+	inboundSvc := &InboundService{}
+
+	email := "keepme@x"
+	c := model.Client{Email: email, ID: "11111111-1111-1111-1111-111111111111", SubID: email, Enable: true}
+	ib := mkInbound(t, 52030, model.VLESS, clientsSettings(t, []model.Client{c}))
+	if err := svc.SyncInbound(nil, ib.Id, []model.Client{c}); err != nil {
+		t.Fatalf("seed linkage: %v", err)
+	}
+	mkTraffic(t, ib.Id, email, 111, 222, 0, 0, true)
+
+	rec := lookupClientRecord(t, email)
+	if _, err := svc.Delete(inboundSvc, rec.Id, true); err != nil {
+		t.Fatalf("Delete(keepTraffic): %v", err)
+	}
+
+	var cnt int64
+	if err := database.GetDB().Model(&xray.ClientTraffic{}).Where("email = ?", email).Count(&cnt).Error; err != nil {
+		t.Fatalf("count traffic: %v", err)
+	}
+	if cnt != 1 {
+		t.Fatalf("keepTraffic delete of an inbound-attached client must preserve its client_traffics row, found %d", cnt)
+	}
+}
+
 func TestGetClientTrafficByEmailReadsClientsTable(t *testing.T) {
 	setupBulkDB(t)
 	svc := &ClientService{}