- Create StarRating component with interactive/readonly modes, amber stars, size sm/md
- Add PersonalRating type and taskCount/avgCostUsd/lastUsedAt to SkillListItem
- Add getRatings and addRating to skillRegistryApi
- Add Rating System section to DesignGuide with all variants
- Fix SkillCard fixture and DesignGuide examples to include new SkillListItem fields
