Wave-assembled from PR #3888 by @RerankerGuo. Conflict resolution: KEY_FILES.md
check-resolvable/skill-frontmatter/skill-trigger-index entries taken as the
PR's current-state prose; the PR's stale pre-fold 'doctor.ts extension' entry
dropped (master already folded it into the main doctor entry).
Co-Authored-By: RerankerGuo <121015044+RerankerGuo@users.noreply.github.com>