fix: don't hold main database update lock when tidying folder databases

internal/db/sqlite/db_service.go

@@ -80,13 +80,12 @@ func (s *Service) periodic(ctx context.Context) error {
 	t0 := time.Now()
 	l.Debugln("Periodic start")
 
-	s.sdb.updateLock.Lock()
-	defer s.sdb.updateLock.Unlock()
-
 	t1 := time.Now()
 	defer func() { l.Debugln("Periodic done in", time.Since(t1), "+", t1.Sub(t0)) }()
 
+	s.sdb.updateLock.Lock()
 	tidy(ctx, s.sdb.sql)
+	s.sdb.updateLock.Unlock()
 
 	return wrap(s.sdb.forEachFolder(func(fdb *folderDB) error {
 		fdb.updateLock.Lock()