- Add LessonsController with GET /Plugins/Lessons/List endpoint
- Add LessonStore DI registration in ServiceRegistrator
- Add lessonsPage.html embedded resource with grouped lesson listing
- Implement IHasWebPages in Plugin for sidebar nav entry
- Add ImplicitUsings/Nullable to csproj for net9.0 compatibility
- Add Microsoft.AspNetCore.App FrameworkReference for MVC
- Fix ServiceRegistrator to match 10.10.x IPluginServiceRegistrator signature