docs: add @openuidev/cli API reference

[AbhinRustagi]

Summary

Adds API reference documentation for @openuidev/cli to the docs site.

The CLI currently has no dedicated reference page, leaving users without a single source of truth for available commands, flags, and options. This PR fills that gap and also establishes a foundation for the page to grow as the CLI expands — for example, to support scaffolding for frameworks beyond Next.js (Svelte, Vue, etc.).

Changes:

• Adds docs/content/docs/api-reference/cli.mdx — full API reference for @openuidev/cli covering openui create, openui generate, export auto-detection logic, the PromptOptions type, and a "See also" section
• Updates api-reference/index.mdx to list @openuidev/cli in the package overview and Cards grid
• Updates api-reference/meta.json to include cli in the sidebar nav

Test plan

• cd docs && pnpm dev — dev server starts without errors
• /docs/api-reference/cli renders with all sections
• Sidebar shows "CLI" under API Reference
• Cards on the API Reference index link to the CLI page correctly

🤖 Generated with Claude Code

[Aditya-thesys]

LG @AbhinRustagi , thanks! for updating the docs

[abhithesys]

Thanks for adding the docs.