chore: deprecate @metamask/design-system-tailwind-preset

[georgewrmarshall]

Summary

@metamask/design-system-tailwind-preset is the Tailwind CSS v3 theme configuration for web consumers. With the migration to Tailwind v4 (#842), this package is superseded by @metamask/design-tokens/tailwind/theme.css.

Steps

• Add deprecation notice to the top of packages/design-system-tailwind-preset/README.md directing consumers to the Tailwind v3 to v4 migration guide
• Update package.json description to indicate deprecated/v3-only status
• Publish a final version with the deprecation notice
• Add npm deprecate message: "This package is deprecated for Tailwind v4 consumers. Use @metamask/design-tokens/tailwind/theme.css instead. See migration guide."
• Update root README.md package list and dependency graph to mark as deprecated
• Update CLAUDE.md to note deprecation status
• Remove design_system_react --> design_system_tailwind_preset edge from the root README mermaid graph (peer dep was removed in Tailwind v4 #842)

Context

The preset remains functional for Tailwind v3 consumers (including any legacy projects). The deprecation is a signal, not a removal — the package should continue to be published and maintained minimally until all known consumers have migrated.

React Native packages (design-system-twrnc-preset) are unaffected and remain on Tailwind v3.