Enhanced extension installation documentation across docs, examples, and the generated install guide. Added Windows, macOS, and Linux-specific paths to help users find the correct installation directory. The dynamic README now shows the machine's actual extensions directory and typical OS paths. Also includes a minor fix removing wide string literal prefix from a path string.
Add a new example extension that displays YouTube dislike counts using the public Return YouTube Dislike API. This is a simplified port of the Anarios/return-youtube-dislike project adapted for Nebula's native extension runtime (content-script only, no Chrome APIs). Includes proper attribution and respects rate limits and GPL-3.0 licensing requirements.