docs: document the complete published package surface

[vishxrad]

Problem

The root README and website API reference do not represent OpenUI's current published package surface.

The repository currently publishes nine packages:

• @openuidev/browser-bundle
• @openuidev/cli
• @openuidev/lang-core
• @openuidev/react-email
• @openuidev/react-headless
• @openuidev/react-lang
• @openuidev/react-ui
• @openuidev/svelte-lang
• @openuidev/vue-lang

However, the root README.md package table lists only react-lang, react-headless, react-ui, and the CLI. In particular, the browser bundle is not discoverable from the main README despite providing the supported CDN/iframe/no-build integration path.

The website API reference is also React-centric and omits the browser bundle, framework-agnostic core, and Vue/Svelte runtimes from its package overview.

Proposed update

Update the package overviews so users can discover the complete supported package surface and quickly choose the appropriate integration path.

Acceptance criteria

• Add @openuidev/browser-bundle to the root README package table with its CDN, iframe, and no-build use case.
• Add the other missing published packages to the root table: lang-core, react-email, svelte-lang, and vue-lang.
• Update the repository structure section to include the current packages.
• Expand the website API/package overview to acknowledge the complete package surface.
• Link each package to its package README, API documentation, or appropriate project page.
• Clearly distinguish framework-agnostic, React, Vue, Svelte, email, and browser-bundle integration paths.

[shogun444]

Hi @vishxrad , I'd like to take this one.

I'll update the README and package overview documentation to match the current published package surface and integration paths.

[ded-furby]

I am opening a docs PR for this issue that updates the root README package matrix and the API reference overview so the missing published packages are discoverable from both entry points.