Agent Skills: code-audit

Codebase-specific smell catalog with calibrated grep recipes: duck-typing at boundaries, yargs argv re-assertions, value-discarding promise tails, console.* in library code, exhaustive `never` over-broad unions, single-method `Pick` deps, `*Like` boundary shape copies. Use for a periodic audit pass, scoping a cleanup PR, after a major refactor, or reviewing a primitive's consumers. Pairs with refactoring (fix mechanics) and post-implementation-review (second-read hub).