docs(06): research phase domain

Phase 6: Carousel Navigation
- Standard stack identified (embla-carousel-react v8.6.0)
- Architecture patterns documented (hook-based carousel, dot indicators)
- Pitfalls catalogued (loop bug with 2 slides, iOS Safari touch handling)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: pineapplestrikesback