Delete a label

Rename or recolour. Omitted fields keep their stored value. A label's team is immutable, so teamId is not accepted — moving a label would detach it from every issue that carries it. A name another label in the same team uses is a 409, compared trimmed and case-insensitively; a label keeping its own name is not a collision. Unlike a cycle, a label has no number to fall back on, so a blank name is a 400 and never clears it. An empty color resets it to the default "#95a2b3". Editing a label changes it on every issue it is attached to. Labels in another org read as 404.