Implement sweep (conic) gradients

[Lorp]

Sweep gradients are not representable directly in SVG. However sweep gradients are available (called conic gradients) in HTML canvas. So if/when canvas output is added to Samsa, it can be implemented. CanvasRenderingContext2D: createConicGradient() method

Sweep gradients are also available in Skia. Because of that, they are available in CanvasKit - Skia + WebAssembly. This was used by @underware to polyfill COLRv1 in Safari for the Plakato Moiré demo.

Sweep ("conic") gradients are also available in CSS:

background-image: conic-gradient(red, orange, yellow, green, blue);

… and this CSS Tricks article talks about including regular DIVs in SVG as <foreignObject>:
My Struggle to Use and Animate a Conic Gradient in SVG