[charts-pro] Allow source/target keywords in sankey link color

[JCQuintas]

Fixes #19447

• Link default color is now palette.text.disabled instead of primary for a softer color in both dark and light themes
• Added source/target keywords to link color

Screen.Recording.2025-09-19.at.17.18.36.mov

[mui-bot]

Deploy preview: https://deploy-preview-19634--material-ui-x.netlify.app/

Updated pages:

• docs/data/charts/sankey/sankey.md

Bundle size report

Bundle	Parsed size	Gzip size
@mui/x-data-grid	0B(0.00%)	0B(0.00%)
@mui/x-data-grid-pro	0B(0.00%)	0B(0.00%)
@mui/x-data-grid-premium	0B(0.00%)	0B(0.00%)
@mui/x-charts	0B(0.00%)	0B(0.00%)
@mui/x-charts-pro	🔺+53B(+0.01%)	🔺+39B(+0.03%)
@mui/x-date-pickers	0B(0.00%)	0B(0.00%)
@mui/x-date-pickers-pro	0B(0.00%)	0B(0.00%)
@mui/x-tree-view	0B(0.00%)	0B(0.00%)
@mui/x-tree-view-pro	0B(0.00%)	0B(0.00%)

Details of bundle changes

Generated by 🚫 dangerJS against 544f002

[codspeed-hq]

CodSpeed Performance Report

Merging #19634 will not alter performance

_{Comparing JCQuintas:sankey-link-color (544f002) with master (48513a6)¹}

Summary

✅ 12 untouched

Footnotes

1. No successful run was found on master (26dbfde) during the generation of this report, so 48513a6 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[prakhargupta1]

I think we should keep color: 'source' as the default (it feels more like a default). If someone wants it to be palette.text.disabled they can do it themselves.

[alexfauquette]

I agree with @prakhargupta1 having looks better to have 'source' as the default value. And introduce a third option like 'neutral' for the gray if we want an easy option that don't requires calling the theme.palette

[JCQuintas]

I agree with @prakhargupta1 having looks better to have 'source' as the default value. And introduce a third option like 'neutral' for the gray if we want an easy option that don't requires calling the theme.palette

neutral they can just select their own imo, so it is easier to just do source/target/color only