fix(handlers): improve tags validation in bulk update

Changed HandleBulkUpdate to check tags array length before assignment
instead of checking for nil, improving consistency with array handling
and preparing for dual-field normalization implementation.

internal/handlers/media.go

@@ -501,7 +501,7 @@ func (h *MediaHandler) HandleBulkUpdate(c echo.Context) error {
 		if update.Updates.Language != nil {
 			updateParams.Language = pgtype.Text{String: *update.Updates.Language, Valid: true}
 		}
-		if update.Updates.Tags != nil && len(update.Updates.Tags) > 0 {
+		if len(update.Updates.Tags) > 0 {
 			updateParams.Tags = update.Updates.Tags
 		}