feat: add A2UI support with OpenUI Lang components

[vishxrad]

Summary

• add the experimental @openuidev/a2ui package
• preserve A2UI v1.0 lifecycle and message envelopes while representing createSurface.components and updateComponents.components as OpenUI Lang statement strings
• provide a framework-neutral client for surface lifecycle, incremental component and data-model updates, actions, RPC, errors, capabilities, and renderer metadata
• provide a React adapter that delegates rendering to @openuidev/react-lang
• publish runtime schemas for both message directions, capabilities, and renderer data-model metadata

Scope

This PR now contains only the new package plus the required workspace lockfile and npm publish selector. The benchmark, example app, root documentation, and changes to lang-core, react-lang, and react-ui have been removed from this PR.

The package keeps statement-level patch handling self-contained so temporarily unreachable components survive until a later update attaches them to root. Hosts can map OpenUI actions to A2UI sourceComponentId values through mapAction; the fallback is root.

Why

We want A2UI to remain the lifecycle and transport protocol. The only wire-level component change is that component arrays contain OpenUI Lang instead of catalog JSON component objects, and the existing OpenUI parser and renderer remain the evaluation path.

Validation

• 21 tests, including React rendering and incremental protocol behavior
• TypeScript typecheck
• package build
• ESLint and Prettier checks
• Publint
• Are the Types Wrong package checks