A test pins `reviewStats`: green crew pulls awaiting a verdict, the median wait for one, and verdicts per reviewer in the window #6697

src/core/review-stats.ts feeds the board's review line. test/review-words.test.ts covers the words and not the read underneath.

Done when test/review-stats.test.ts seeds runs, checks and reviews in a fresh database and shows:

• [ ] awaiting counts only open pulls an agent wrote, whose head is green, with no verdict on that head. A person's pull, a red head, a merged pull, and a verdict on an older head with none on the new one each count, or not, as the doc comment says.
• [ ] latencyMs is the median from a head's first passing check to an agent's verdict, odd and even counts both, and null with none in the window.
• [ ] byReviewer counts only verdicts since since, most first, and never a person's review.

If a case shows a bug, fix it in src/core/review-stats.ts and say which one.

Files: test/review-stats.test.ts, src/core/review-stats.ts