Update animated-intro based on feedback

- 5 acts in the restructured order (Invitation → Skewed Pool → Representative? → Naive Selection → Targets to Fairness)
- Terminology box with candidates/panellists in Act 1
- Clickable note popups replacing footnotes
- 618 valid panels computed correctly
- Example panels both contain Omar and Priya, sorted alphabetically
- Algorithm card blurbs reference representativeness and fairness
- Softened language throughout intersections and skew discussion

Author: foobacca