Artifact tool guidance expanded to cover creating and reading design systems

The internal instructions that tell the model how to find and use artifact types now explicitly mention design systems, including ones built from your own codebase, as something the quickstart and list-types steps should handle. A new rule classifies design-system requests under an intent: "other" category, and a new instruction tells the model to look up and read an existing design-system artifact when answering questions about it, falling back to searching your files if no such artifact is listed.