v2.40.0

Added — a back-reference beside every anchored rule (W2137)

Canon entry edit-site-back-reference requires prose beside every governed-rule statement naming the canon by path and the entry id, and the drift check now implements it as a property, so an anchor standing alone is reported. Four paragraphs close this port's five anchored statements. The decision matrix and its precedence ordering are back-referenced in skills/stride-subagent-workflow/SKILL.md, where this port keeps its matrix rather than in the workflow skill, with one paragraph naming both entries.

Placement respects two assertions this repository owns. The suite requires the review-round-cap anchor to sit exactly one line above the ceiling sentence, so that paragraph goes at the end of its section instead — 47 lines down — and names an elided <!-- canon:review-round-cap ... --> so a reader landing there has something to grep for. The suite reads only the first match of the real anchor literal, so a version-less second occurrence cannot move the offset it checks.