The fold buckets all three skill-content shapes the harness injects — the
<available_skills> catalog digest, a user-explicit /name invocation's
instructions message, and the content a skill-tool load returns — into a
new 'skill' composition category instead of burying them in inject/tool
(closes#66). Skill-tool loads keep their tool identity stamped, so the
call tallies, hit counts, and failure marking are unchanged.
stateVersion 18 → 19: the per-category sums change shape, so cached rows
refold from the durable log on upgrade (docs/compatibility.md).
The trend chart, overview, Token donut, stats, and the Context browser all
gain the seventh bucket (orange-500); the browser's skill section pins its
rows like injects, so long sessions keep listing what the sums count.