Copy actual manifest files from webpack build if they exist

Instead of always creating empty stub manifest files, try to copy the
actual files from the Pro dummy webpack build first. This ensures RSC
tests have proper module mappings when the webpack build successfully
generates them.

Falls back to empty stubs if the files don't exist, preserving the
hang-prevention behavior.

Author: justin808

packages/react-on-rails-pro-node-renderer/scripts/setup-test-env.sh

@@ -26,10 +26,19 @@ mkdir -p "$ROOT_DUMMY/public/webpack/test"
 echo "Copying bundles to test locations..."
 cp "$PRO_DUMMY/ssr-generated"/*.js "$ROOT_DUMMY/ssr-generated/"
 
-# Create stub manifest files
-echo "Creating stub manifest files..."
-echo "{}" > "$ROOT_DUMMY/public/webpack/test/react-client-manifest.json"
-echo "{}" > "$ROOT_DUMMY/ssr-generated/react-server-client-manifest.json"
+# Copy or create manifest files
+echo "Copying manifest files..."
+if [ -f "$PRO_DUMMY/public/webpack/test/react-client-manifest.json" ]; then
+  cp "$PRO_DUMMY/public/webpack/test/react-client-manifest.json" "$ROOT_DUMMY/public/webpack/test/"
+else
+  echo "{}" > "$ROOT_DUMMY/public/webpack/test/react-client-manifest.json"
+fi
+
+if [ -f "$PRO_DUMMY/ssr-generated/react-server-client-manifest.json" ]; then
+  cp "$PRO_DUMMY/ssr-generated/react-server-client-manifest.json" "$ROOT_DUMMY/ssr-generated/"
+else
+  echo "{}" > "$ROOT_DUMMY/ssr-generated/react-server-client-manifest.json"
+fi
 
 echo "✓ Test environment setup complete!"
 echo ""