complexity: match a moved function by its unique name

A pure move fired the gate as a new function: file+name identity made relocating an over-limit function to another file — the gate's own advice — exit 1, and a replay over main found a merge (#2679, compactCodex at 53) it would have blocked for exactly that. A key with no base match now falls back to the bare name when that name occurs exactly once in each tree, judging the function against its old value. A copy next to a surviving original is not unique in head, and init/_ are never unique, so neither can borrow an exemption this way.