Drop an unused Default on CarriedOver

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

server/src/registry.rs

@@ -340,7 +340,6 @@ fn component_id(component: &Component) -> ComponentId {
 /// component's directory decides which builds are its own, a reused name
 /// is a different component, and handing it the old one's package or
 /// commit would be wrong until that component happened to be built.
-#[derive(Default)]
 struct CarriedOver {
     packages: HashMap<ComponentId, String>,
     chosen: HashMap<ComponentId, crate::config::Choices>,