nfl/react-helmet ? reverse-engineered prompt

Build me a small React library called React Helmet that lets me control everything in the document head from inside components. I want to be able to wrap parts of my app with a Helmet component and set things like the page title, meta tags, link tags, script tags, style tags, and attributes on html and body. If multiple Helmet components are nested, the deeper one should win for duplicate tags, but repeated tags in the same component should still be preserved for things like icons. It should work in normal React apps and also support server side rendering, with a way to collect the head output after rendering on the server. Please make it feel simple and beginner friendly, with a clean API, good examples, and tests that cover the main behavior. If you need to check current React docs or build tooling details, look them up online first.