dyad pro: do not show upgrade banner (#1537)

<!-- CURSOR_SUMMARY -->
> [!NOTE]
> Hide the “Upgrade to Dyad Pro” link in `ChatErrorBox` when
`isDyadProEnabled` is true.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
424cd04f85385f923548b3fc54b4c83625992ade. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

src/components/chat/ChatErrorBox.tsx

@@ -99,12 +99,14 @@ export function ChatErrorBox({
     <ChatErrorContainer onDismiss={onDismiss}>
       {error}
       <div className="mt-2 space-y-2 space-x-2">
+        {!isDyadProEnabled && (
           <ExternalLink
             href="https://dyad.sh/pro?utm_source=dyad-app&utm_medium=app&utm_campaign=general-error"
             variant="primary"
           >
             Upgrade to Dyad Pro
           </ExternalLink>
+        )}
 
         <ExternalLink href="https://www.dyad.sh/docs/faq">
           Read docs