Agent Skills: skill-portfolio-review

Audit the entire skill portfolio for redundancy, misplacement, staleness, and context bloat. Use for /skill-portfolio-review, 'review my skills', 'clean up skills', 'are any skills redundant', or after adding 3+ new skills since last review. Produces DELETE/MERGE/REFRAME/KEEP recommendations per skill. NOT for auditing a single skill (/skill-quality-gate) or project quality (/audit).