Implement closed typed semantic review with immutable proposals

crates/oa-core/tests/workflows.rs

@@ -42,6 +42,7 @@ fn make_trace(p: &mut Project, oa: Id, sa: Id) -> Id {
         baseline: Some(TraceBaseline {
             oa: p.properties(oa).unwrap(),
             sa: p.properties(sa).unwrap(),
+            semantic: None,
         }),
     };
     p.traces.insert(id, t);