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.
Adds an extension manager that loads unpacked extensions from the user data extensions directory, persists enabled state, and injects matching content scripts on page load. The settings Plugins page now shows installed extensions, supports reload/toggle actions, and includes an example Hello Nebula extension.
Andrew Zambazos