Add missing TestingStreamableComponent for streaming tests

The component was referenced in spec/helpers/react_on_rails_pro_helper_spec.rb
but was never created. This was causing test failures in the
rspec-dummy-app-node-renderer CI job.

The component is a simple test component that returns the expected
markup for streaming SSR tests.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: justin808

react_on_rails_pro/spec/dummy/client/app/ror-auto-load-components/TestingStreamableComponent.jsx

@@ -0,0 +1,15 @@
+'use client';
+
+import React from 'react';
+
+// Simple test component for streaming SSR tests
+function TestingStreamableComponent({ helloWorldData }) {
+  return (
+    <div>
+      <div>Chunk 1: Stream React Server Components</div>
+      <div>Hello, {helloWorldData.name}!</div>
+    </div>
+  );
+}
+
+export default TestingStreamableComponent;