List project factory PR costs

Lists the factory PRs behind the Cost per PR card (GET .../factory/metrics/cost) for the requested window (filter[timestamp][gte] to the exclusive filter[timestamp][lt], at most 90 days, the last 7 days when neither is given), counted as the card counts them: one row per PR whose opening run, or any follow-up, is counted in the window. firstRunCredits and followUpCredits are the credits counted in the window, so the rows add up to the card’s current.prCredits, and the rows with openedInWindow number its current.prsOpened. openedAt is when the opening run was created, and loop and skill are the opening run’s project Loop (null when no Loop of the project started it) and its skill without its version. runs lists the PR's counted runs, oldest first, at most 20, and runsTruncated says there are more. filter[opened] keeps the PRs whose opening run is counted in the window (inRange, the rows with openedInWindow) or the rest (earlier), so an opening run still unfinished counts as earlier. sort is -credits (the default) or -openedAt, ties broken by URL; page links carry the resolved window.