Refine portfolio copy and enable photo gallery

Content improvements:
- Remove "Over 15 years" opening (less arrogant tone)
- Simplify About page by removing redundant "Architecture from the Source" section
- Reframe LLM discussion as question-led exploration vs. declarative statements
- Update Statsbomb title to "Sports Data Collection" (broader scope)

Features:
- Enable PhotoGallery component in Statsbomb case study
- Add photo gallery design documentation
- Add image optimization script for gallery

UI fixes:
- Fix MermaidDiagram chevron positioning (remove absolute positioning)

Author: saadshahd