feat: implement Angular Day 9-14 component patterns - Day 9: Custom two-way binding with ToggleComponent (@Input/@Output pattern)
- Day 13: Content projection with ng-content multiple selectors and ngProjectAs
- Day 14: Template rendering with ng-template, ngTemplateOutlet, ng-container
- Add interactive shopping cart demo with service sharing
- Implement responsive UI with Tailwind CSS
- Add comprehensive documentation and interactive examples
- Create reusable components: ProgressBar, AuthorList, Toggle, Card, Modal
- Setup proper TypeScript typing and RxJS patterns