fix(clients): store client group names trimmed

The groups page lists clients.group_name as stored, while every group
action trims the name it is given. A name with surrounding white space,
saved by a node snapshot or by a client edit, was listed as a separate
group, and deleting, renaming or resetting that row acted on the real
group of the trimmed name instead.

Group names are trimmed wherever a client record is built or updated,
and a one-time seeder folds stored names onto their trimmed form.

internal/web/service/client_crud.go

@@ -923,7 +923,7 @@ func (s *ClientService) Update(inboundSvc *InboundService, id int, updated model
 	// including the empty string that removes the client from its group.
 	if err := database.GetDB().Model(&model.ClientRecord{}).
 		Where("id = ?", id).
-		UpdateColumn("group_name", updated.Group).Error; err != nil {
+		UpdateColumn("group_name", strings.TrimSpace(updated.Group)).Error; err != nil {
 		return needRestart, err
 	}