LFM 0.5.0 lands: the table of contents deletes its local scaffolding, and starts leaving callout headings alone

The helpers this site was carrying locally shipped in the package, so `toc-types.ts` was deleted rather than migrated — which was the point of writing it that way. `inContainer` arrived with it, so headings nested inside callouts no longer show up as phantom sections. Also: the ToC was rendering twice on every guide, and had been since it shipped this morning.