Enable server-side rendering by default in generator template

- Change index.html.erb template from prerender: false to prerender: true
- Demonstrates SSR capabilities out of the box for new React on Rails apps
- Provides better initial experience with improved SEO and performance
- Users can still disable by changing to prerender: false if needed

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

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

Author: justin808

lib/generators/react_on_rails/templates/base/base/app/views/hello_world/index.html.erb.tt

@@ -1,2 +1,2 @@
 <h1>Hello World</h1>
-<%%= react_component("<%= config[:component_name] %>", props: @hello_world_props, prerender: false) %>
+<%%= react_component("<%= config[:component_name] %>", props: @hello_world_props, prerender: true) %>