v1.0.31

v1.0.31

CI: markdown-reference verifier. New verify-references workflow (permissions: contents: read, stdlib-only script) fails any PR or push that leaves a backticked .md reference unresolved: bare skill-local (references/X.md, sub-skills/X.md, sibling X.md), nested (../../../references/X.md) and root-relative (skills/<skill>/SKILL.md) forms, scanning root SKILL.md, shared references/ and everything under skills/. Ported from x-skills #15 (thanks @moinerus) and extended after codex review.

Fixes. Sub-skill and skill-local reference docs cited shared root references one directory level short (../../references/); corrected to ../../../references/. No behaviour change for the skills themselves beyond the previously dead links now resolving.