docs: add migration guide from json-render (Fixes #354)

[SparshMishra09]

Summary

Adds a new documentation page that helps users move from json-render (vercel-labs/json-render) to OpenUI Lang. The page is wired into the OpenUI Lang docs under the Advanced section via docs/content/docs/openui-lang/meta.json.

Closes #354.

Contents

• Concept-by-concept mapping table from json-render to OpenUI Lang
• How to convert a defineCatalog to defineComponent + createLibrary
• Translating JSON spec / elements to OpenUI Lang statements and references
• Replacing catalog.prompt() with @openuidev/cli generate + generateSystemPrompt
• Replacing the registry and <Renderer spec registry /> with <Renderer library response />
• Migrating / / / to `` and expressions
• Migrating catalog actions to Action, onAction, and @ToAssistant
• Migrating data access to Query, Mutation, and toolProvider
• Translating createSpecStreamCompiler to OpenUI's streaming-friendly parser
• Recommended migration sequence and a checklist
• Links to related OpenUI documentation (overview, defining components, system prompts, renderer, reactivity, queries/mutations, incremental editing)

Files

• docs/content/docs/openui-lang/migration-from-json-render.mdx (new, 400 lines)
• docs/content/docs/openui-lang/meta.json (registered the new page under Advanced)

Validation

• Manual review of the MDX structure and internal links
• Cross-references resolve to existing pages (overview, defining-components, system-prompts, renderer, interactivity, reactive-state, queries-mutations, incremental-editing, comparison)
• Code examples match the API surface documented in the OpenUI Lang docs
• No runtime code changes — documentation-only contribution per the issue scope

Notes

• Documentation-only change. No runtime package, no test fixtures, no build configuration changes.
• Page lives under the same Advanced section proposed by maintainers in issue Migration guide from json-render #354.

[vercel]

@SparshMishra09 is attempting to deploy a commit to the thesys-devs Team on Vercel.

A member of the Team first needs to authorize it.

[SparshMishra09]

Hi maintainers — quick heads-up that this PR is currently merge-blocked by the Vercel preview deploy check, not by anything in the diff itself.

The Vercel bot is asking a member of the thesys-devs team to authorize the GitHub integration so the deploy job can run:

https://vercel.com/git/authorize?team=thesys-devs&slug=thesys-devs&teamId=team_VFrH0y6CmDLp2ZhQmgA485os&type=github&job=%7B%22headInfo%22%3A%7B%22sha%22%3A%2285d2b3134295b942a27768a4ecb1033fd29e8fe3%22%7D%2C%22id%22%3A%22QmdvUoQzyustMExw5nreaiCXsCDw9Fkp1NKqXMbHEExAU8%22%2C%22org%22%3A%22thesysdev%22%2C%22prId%22%3A1124%2C%22repo%22%3A%22openui%22%7D

Could someone with access to the Vercel team please approve the integration so the docs preview can build? Once that is done I am happy to address any review feedback, and the rest of the PR (Closes #354 — json-render migration guide under docs/content/docs/openui-lang/) is ready to go.

Thanks!

[SparshMishra09]

Hi maintainers — small follow-up on the merge blockers, in case it helps triage.

There are currently two independent maintainer-side actions keeping this PR from being merged, not one:

1. Vercel team integration — the Vercel preview deploy check is failing because the GitHub integration has not been authorized for the thesys-devs Vercel team. A team member can authorize it here: https://vercel.com/git/authorize?team=thesys-devs&slug=thesys-devs&teamId=team_VFrH0y6CmDLp2ZhQmgA485os&type=github&job=%7B%22headInfo%22%3A%7B%22sha%22%3A%2285d2b3134295b942a27768a4ecb1033fd29e8fe3%22%7D%2C%22id%22%3A%22QmdvUoQzyustMExw5nreaiCXsCDw9Fkp1NKqXMbHEExAU8%22%2C%22org%22%3A%22thesysdev%22%2C%22prId%22%3A1124%2C%22repo%22%3A%22openui%22%7D

2. First-time contributor workflow approval — the PR page also shows "1 workflow awaiting approval". GitHub requires a maintainer to approve the first workflow run from a new contributor before CI can execute.

Either of those is enough to clear the merge-blocker on its own; both need to be addressed before the Vercel preview can build and the red X can turn green.

No code changes are needed from my side. The diff (Closes #354 — json-render migration guide under docs/content/docs/openui-lang/) is unchanged and ready to merge. Happy to address any review feedback once these are sorted.

Thanks again!