feat(review): tell reviewers their time budget in the prompt

A reviewer that knows its deadline paces itself; one that doesn't runs its full-depth pipeline and gets killed mid-verify with every finding discarded — observed live: a claude-code review was ~90% done when the timeout killed it and the run recorded nothing from those 10 minutes.

ComposeReviewPrompt now renders the effective per-reviewer timeout as a pacing instruction. Only a positive RunConfig.ReviewerTimeout renders (zero = unresolved, negative = disabled; inventing a default in either case could contradict the orchestrator's real deadline), and the multi-agent path now sets ReviewerTimeout on each per-agent RunConfig — previously only the single-agent path carried it.