Review PR Comments

Handle real review feedback on an existing PR. This is an on-demand, exception path: most PRs have no comments because cloud auto-review is disabled and the heavy review already happened locally (ship-it's delivery gate). Do not summon bot reviews (@codex review, @coderabbitai review), and never treat a bot's silence as something to wait for.

Process, at most TWO rounds (a round = collect → triage → one batched commit → push → required CI green on the new head):