feat(zero-noise): signal verdicts + published precision on /status #5524

Zero-Noise build-map item 1 (agent-built, coordinator-rebased)

The number nobody in developer tooling publishes, now computed and public:

• Verdicts: one-click "✓ useful / ✗ wrong" on AI review findings (predicate: pr_comments.is_ai_review — the column every existing surface already means by "AI review comment"; the summary-marker approach was rejected as it misses inline findings). PR author or write access may judge — deliberately narrower than thread-resolve, since verdicts feed a published figure. Migration 0127, unique standing verdict per signal with upsert.
• /status "Signal precision": precision = acted/(acted+dismissed) over rolling 30 days, always rendered beside its sample size, publishing only at ≥10 judgments — below that, the honest empty state with real counts. Every state carries the provenance line: "Computed from developer verdicts on AI review findings, not claimed." Three states including store-unreadable; no path fabricates a number.
• Copy-honesty tripwires extended to pin the section title, provenance sentence, empty-state path, publication floor, and rate-never-without-sample-size.

Zero new env vars. Typecheck clean; 43 tests green across precision/copy-honesty/exclusion-rot (7 DB-gated skips run in CI).

Next per the doctrine's build map: verified-before-shown (the skeptic pass), then Actions compatibility.

🤖 Generated with Claude Code