code4craft/webmagic ? reverse-engineered prompt

Build me a Java web crawler framework like WebMagic that makes it easy to scrape websites without a lot of setup. I want the core flow to handle downloading pages, managing URLs, extracting content, and saving results, with a clean API that feels simple to use. It should support both the normal processor style and the annotation style so someone can define a crawler with a plain Java class and start running it quickly.

Please include support for multiple threads, and make it easy to extend with extras like Selenium or other helpers if needed. Add a few working examples for common cases like crawling GitHub style pages, and make sure the project is organized as a reusable library with clear modules. If you need to check current docs or best practices, look them up online.