Adds a "PNG" button beside "JSON" in the pattern editor footer. It
rasterises the normalised motif (solid black strokes on a white
background, line width scaled to the cell size, ~800 px on the
longer axis) to a canvas, pulls a PNG blob via toBlob, and triggers
a download with the same safe-name slug as the JSON export.
The existing "Download" button is relabelled "JSON" so the two
outputs are distinguishable.
https://claude.ai/code/session_01KNdXjQczMCRGMK7K3Qderw
52615a5086