Create a Brand for the Brand Toolkit

Generates a Digital Experience brand — one brand.json file — from a user's description, and writes it where the VS Code Brand Toolkit will discover it, so the user can immediately load, edit, and preview the brand.

A brand is a single JSON object of design tokens: colors (colorScheme), a font catalog and base font (fontFamily / baseFontFamily), size/spacing/border scales, per-role typography, and buttonStyleGroup definitions. Most of it is fixed structure with internal references; you create a brand by starting from a known-good template and changing only the leaf values (colors, font choice, border radius, base size) plus a unique name.

The Brand Toolkit owns everything downstream: it computes derived hover colors, compiles the --tm-* CSS, and manages the active-brand config on Save. Your job is just the brand.json.