- Add compute_overtone_shift(): tracks semantic gravity movement across windows
even when party ordering stays the same
- Update _generate_report() with overtone shift section including dimension-level
analysis and inflection point detection
- Update methodology section to reflect new metrics
- All 12 tests pass
Key finding: no axes exceed 0.7 stability threshold — semantic features
defining each SVD axis shift significantly across windows (0.06-0.51 range)