✅ Clean source file headers: 'Module X:' → clean descriptive titles
✅ Regenerate overview pages with clean headers
✅ More flexible content that works in any context
✅ Numbers still provided by book TOC structure
Changes:
- Remove 'Module X: ' prefix from all source file headers
- Headers now focus on descriptive content titles
- Book maintains proper chapter ordering via _toc.yml
- Content is more reusable across different presentations