docs(frontend): name the UI section by its new title, User Interface

K3 #27179 renamed the content/docs/ui section from "Views & Apps" to
"User Interface"; the frontend landing's pointer follows it.

Claude-Session: https://claude.ai/code/session_01L9qibzngYyRjmvNxjkfVyd
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

content/docs/frontend/index.mdx

@@ -12,7 +12,7 @@ UI runs and who renders it.
 | Read and write ObjectStack data from your own front-end | [Client SDK](/docs/api/client-sdk) (`@objectstack/client`) | Your app, any framework |
 | Render ObjectStack views, forms and dashboards in your own React app | The ObjectUI SDK, below | Your React app |
 
-The first path is metadata like any other page, so it is documented with [Views & Apps](/docs/ui).
+The first path is metadata like any other page, so it is documented with [User Interface](/docs/ui).
 The rest of this section is the ObjectUI SDK.
 
 ## The ObjectUI SDK