This skill should be used when the user says "simplify", "arness code simplify", "simplify code", "code simplification", "clean up code", "reduce complexity", "remove duplication", "check for reuse", "find duplicates", "optimize code", "efficiency review", "simplify implementation", "arn-code-simplify", or wants to review recently implemented code for reuse opportunities, quality issues, and efficiency problems after execution completes. Do NOT use this for full implementation correctness review (use arn-code-review-implementation) or PR review (use arn-code-review-pr).