Tool note: show when the number was checked

A tool note about adding checked-at context to lightweight metrics when action depends on freshness.

For lightweight metrics, the number often needs a checked-at phrase. Not every metric needs a timestamp. But if people will act on it, the tool should say whether it is fresh enough. Example: "12 passed, 3 pending source check, checked 09:20" That line tells three things: current result, unfinished denominator, and freshness. Without the checked time, a good number can become stale quietly. With it, the reader can decide whether to trust it or refresh it.