Changes touching this path

• the three surfaces describing the perf gate stop disagreeing about what an absent metric means, because an explained absence is reported and exits 4 exactly as an unexplained one does, and each surface now points at the one that owns a fact rather than restating it — including the exit code itself, named once in loot-perf and read from that name by both the gate binary and the land (#1403) dc3ccf75 · dbf3dbe6…

Renames are not followed. loot's tree maps a path to an address, so a rename is a delete and an add. This list is the history of the name, not of the bytes.