Agent Skills: pr-overview

Pull a PR from GitHub, run parallel review agents (code reuse, quality, efficiency, spec adherence) in read-only mode, surface unresolved comments, and write a self-contained HTML overview page to the repo root. Use whenever the user wants a read-only summary of a PR before deciding what to do — phrases like "overview of PR X", "summarise this PR", "what's the state of PR X", "give me an HTML overview", or any time they want a browseable artifact without touching the code.