demo: set turbopack.root to silence Next.js workspace root warning

Next.js 16 infers the workspace root by walking up to the topmost
lockfile, which lands on ~/package-lock.json. Setting turbopack.root
to the repo root gives the correct resolution scope for the symlinked
@ably/ai-transport dependency.

Author: mschristensen

demo/vercel/react/use-chat/next.config.ts

@@ -1,7 +1,13 @@
+import path from 'path';
 import type { NextConfig } from 'next';
 
+const repoRoot = path.resolve(__dirname, '..', '..', '..', '..');
+
 const nextConfig: NextConfig = {
   serverExternalPackages: ['jsonwebtoken', 'ably'],
+  turbopack: {
+    root: repoRoot,
+  },
 };
 
 export default nextConfig;

demo/vercel/react/use-client-transport/next.config.ts

@@ -1,7 +1,13 @@
+import path from 'path';
 import type { NextConfig } from 'next';
 
+const repoRoot = path.resolve(__dirname, '..', '..', '..', '..');
+
 const nextConfig: NextConfig = {
   serverExternalPackages: ['jsonwebtoken', 'ably'],
+  turbopack: {
+    root: repoRoot,
+  },
 };
 
 export default nextConfig;