Add 'legacy' theme variables to Salt Styles Library in Figma

[pseys]

Connect legacy palette variables to characteristics within the Salt Next Styles Library.

• Simplify Salt (Next) Style library Figma variable collections #4113
• Test separating Accent selection from Mode
• Update POC libraries to use new theme references #4233
• Test corner radius presets across each proposed theme #4234
• Test palette relationship to remove independent Mode selection #4235
• Test solutions for handling font-size differences between Themes #4279

Considerations

• The characteristic variables will need modes applied; Salt Next and Salt Legacy (TBC)
• Each characteristic variable mode will need to be mapped to a different set of palette variables – the Salt Next characteristics are already aligned to Accent / Mode in the styles library. Salt Legacy will need to map to a 'Mode' only switch, either in the same file or from a different library (TBC)
• When creating a new design, components will default to Salt Next, but designers will have the ability to toggle to Salt Legacy if they wish, however, they will have to set mode separately

Dependent on #3843 and #3844

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Espresso Goal : write up the approach and share with Stakeholders and get feedback

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Frappe Goal: write up the approach and share with Stakeholders and get feedback

• how do we refer to the themes
• how much we restrict the use of theme next styling options with the legacy theme

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poc working - getting feedback

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Revised Frappe Goal: get all color variables in place by EOS with no carryover ,
Next Sprint: report back on strategy and agree approach based on stakeholder feedback

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Galao Goal: agree on the direction and create smaller tasks by end of wk1

[pseys]

Changing name of issue from to Connect legacy palette variables to characteristics in Figma Add 'legacy' theme variables to Salt Styles Library in Figma

[pseys]

Successfully separated Accent from Mode as part of the POC

[pseys]

Galao Goal: agree on the direction and create smaller tasks by end of wk1

Next steps have been broken out as smaller sub-tasks and progressed updated.

[pseys]

The Brine POC has been successful. Next steps have been created as new issues.

[pseys]

Initial POC complete