What problem does this address?

When creating a global style variation (theme style variation? The combined style under "Browse styles") using an alternative theme.json file, there is no way to reference an existing color palette or typography preset.
This means that the palette and typography settings need to be duplicated: Once in the file for the preset, and once in the combined style variation, which is twice the amount to maintain.

What is your proposed solution?

Introduce a way to reference presets in the other JSON files.
If I have a palette with the slug "01-pink" I would like to be able to reference it similar to this:

	"settings": {
		"color": {
			"palette": "ref: 01-pink"
			....