Pin next to ^16.2.6 to avoid broken 16.3.0-preview.0 release

npm's 'latest' dist-tag for next currently points to 16.3.0-preview.0,
whose @next/swc-linux-x64-gnu binary is not published, so 'next build'
fails with a 404 whenever the lockfile is regenerated.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: brianstrauch

nextjs-ecommerce-oneclick/package.json

@@ -24,7 +24,7 @@
     "@temporalio/envconfig": "^1.18.0",
     "@temporalio/worker": "^1.18.0",
     "@temporalio/workflow": "^1.18.0",
-    "next": "latest",
+    "next": "^16.2.6",
     "react": "^18.2.0",
     "react-dom": "^18.2.0",
     "react-toastify": "^8.0.3",