- Add scripts/generate-perf-charts.py for matplotlib visualizations
- Update generate-perf-report.sh for versioned directories (reports/TAG/)
- Add make perf-charts and make perf-all targets
- Add GitLab CI perf-report job to auto-commit after tagged releases
- Generated 6 charts for 4.2.0: dashboard, duration, histogram, leaders, etc.
Each release now gets its own reports/TAG/ directory with:
- perf.json (raw timing data)
- perf.md (markdown report)
- chart-*.png (6 visualizations)
