Chart palette: colorblind-safe categorical scale

Our categorical chart palette fails for deuteranopia: series 2 and 4 are indistinguishable. We need a colorblind-safe scale that still matches the brand.

Constraints

• Minimum 8 distinguishable categorical steps
• Each step readable against both --background values (light/dark)
• Sequential and diverging ramps derived from the same anchors

Color should never be the only channel encoding a data series.— a11y guidelines, charts section