Agent Skills: lens-review

One-pass multi-perspective PR review that posts findings as a single consolidated PR comment. /frame derives the review lenses that fit the diff, plus a gap scan, over only the files changed in a PR; each lens analyzes in isolation, then the findings are adversarially cross-verified before the survivors are posted. Composes prothesis:frame and syneidesis:gap. User-invoked via /lens-review.