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

## 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 With the migration to Tailwind v4 (#842), this package is superseded by `@metamask/design-tokens/tailwind/theme.css`.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](../design-tokens/MIGRATION.md#tailwind-css-v3-to-v4)
- [ ] 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 #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.

Start with packages/design-system-tailwind-preset/README.md, its package.json, the root README.md, and CLAUDE.md. Review the Tailwind v3 to v4 migration guide at packages/design-tokens/MIGRATION.md#tailwind-css-v3-to-v4 and the release workflow before making the documentation and metadata updates. Done means the package is clearly marked as deprecated while remaining available for Tailwind v3 consumers, with the final version and npm deprecation message published.

Written by the indexing model from the issue text.