Generate a 1D barcode as PNG or SVG: EAN-13, EAN-8, UPC-A, Code 128, Code 39 or ITF-14. Validates the structure and check digit for each symbology — EAN/UPC/ITF compute a missing check digit or reject a wrong one. Options: format (png/svg), scale (module px 1-10), text (human-readable line, default on). Returns the raw image. Generation only — reading a barcode from an image is out of scope.