- Fix stale Part 2 cross-references to link to rl/SKILL.md
- Add McCandlish + Slavv back to parent Sources (cited in Part 7)
- Add back-links from refs/ files to parent SKILL.md
Moved 6.1 (static analysis grep patterns) and 6.2 (diagnostic code
snippets) to refs/static_analysis.md and refs/diagnostics.md.
Triage tree (6.3) stays in main with references to the ref files.
ml_debug/SKILL.md reduced from 7229w to 5093w (~30% from original).