feat(backup): name DB backup files after the server address

Panel downloads and Telegram backups were always named x-ui.db / x-ui.dump, so backups from different servers were indistinguishable. Name them after the panel address instead: the configured web domain, or the public IP (IPv4 before IPv6) when no domain is set, falling back to x-ui.

Centralized in ServerService.BackupFilename(); host is sanitized to the getDb filename charset (IPv6 colons become hyphens) and read from the mutex-guarded LastStatus to avoid racing the status goroutine.

internal/web/service/tgbot/tgbot_report.go

@@ -10,7 +10,6 @@ import (
 	"time"
 
 	"github.com/mhsanaei/3x-ui/v3/internal/config"
-	"github.com/mhsanaei/3x-ui/v3/internal/database"
 	"github.com/mhsanaei/3x-ui/v3/internal/database/model"
 	"github.com/mhsanaei/3x-ui/v3/internal/eventbus"
 	"github.com/mhsanaei/3x-ui/v3/internal/logger"
@@ -403,10 +402,7 @@ func (t *Tgbot) sendBackup(chatId int64) {
 	// Send database backup (SQLite file, or a pg_dump archive on PostgreSQL)
 	dbData, err := t.serverService.GetDb()
 	if err == nil {
-		dbFilename := "x-ui.db"
-		if database.IsPostgres() {
-			dbFilename = "x-ui.dump"
-		}
+		dbFilename := t.serverService.BackupFilename()
 		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
 		document := tu.Document(
 			tu.ID(chatId),