- Add matrix_mode to XY Matrix (full/upper_triangle/diagonal_only)
- XY Plot can render triangular inputs as full NxN with lower triangle masked
- Add XY Cell Prefix node to name per-cell outputs (aligns with matrix_mode)
- Update ArtistBlendXYPlot_Test workflow
- Make columns/x_labels/y_labels forceInput so they can receive connection from XY Matrix
- Fix workflow JSON links for SaveImage (now correctly saves the XY Plot big image)