Generate Astryx design system components, themes, and layouts for React 19 applications. Use when building UIs with @astryxdesign/core, creating or extending themes with defineTheme, styling components with StyleX or Tailwind, scaffolding pages from templates, migrating from shadcn or Radix, or working with the Astryx CLI and MCP server. Also use when converting plain descriptions into Astryx component code or validating existing Astryx code against system conventions.