Grouped bars of LOC, tokens, cost and time as a % of the no-skill baseline
(lower is leaner/cheaper/faster), plus a separate safety strip (baseline,
caveman and ponytail 100%; yagni-oneliner 95%). System-gray palette so it reads
on both GitHub themes. The chart commits landed after #158 had already
squash-merged, so this brings the chart onto main.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
