feat: spike design tokens / branding.theme overrides

[patoperpetua]

Summary

• Draft spike for incremental UI theming discussed in Customize the appearance (theming) #1727 / Custom UI Theming  #3559
• Maps semantic colors (and a few related tokens) to CSS custom properties with current palette as fallbacks
• Adds optional branding.theme config overrides that re-inject :root vars at runtime
• Defaults are unchanged when branding.theme is omitted

This is intentionally small and incomplete — meant to validate direction with maintainers before expanding coverage / dark mode / next-ui work.

Example

branding:
  theme:
    primary: '#112f4e'
    background: '#f5f6f8'
    text: '#798291'
    textLead: '#313d3e'
    status:
      draft: '#70399f'
      in_review: '#754e00'
      ready: '#005614'

Notes / non-goals for this draft

• Not all hard-coded hex values across widgets are tokenized yet
• No dark mode yet
• No CMS.registerTheme() API yet
• Not a next-ui port

Test plan

• Unit tests for token helpers (themeTokens.spec.js)
• Config schema accepts branding.theme and rejects unknown keys
• Manual: run CMS with branding.theme.primary set and confirm header/active accents + body background pick up overrides
• Manual: omit branding.theme and confirm UI looks identical to current main

Refs: #1727 #3559

Made with Cursor

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