feat(people): enhance person detail pages with merged cast/crew credits and improved UI
- Merge cast and crew credits in filmography when person has multiple roles
- Add biography truncation with 'Show more/less' toggle
- Display dynamic backdrop images from filmography on person pages
- Separate directors from other crew in crew sections
- Add metaText support to display role information on poster cards
- Update README with clearer feature list and improved structure
- Add backdrop_path field to filmography items
- Update API generated types for new person DTOs