Dsh Theme Palettes

Key features

• Light appearance uses — a dropdown offering Default plus every registered palette.
• The host half registers the theme-palettes namespace on the Host settings seam, so writes land in the same user settings document as first-party namespaces and the wire exposes the namespace to the browser.
• Duplicate ids throw — pick a unique id.
• Dark appearance uses — a dropdown offering Default plus every registered palette.
• A catalog list showing each palette's two-tone preview (base + accent), label, id, and a built-in/third-party marker.