cargo: preserve build failures in result wrapper

cli/src/cargo_actor.rs

@@ -72,6 +72,12 @@ impl std::fmt::Display for BuildFailure {
 
 impl std::error::Error for BuildFailure {}
 
+impl From<anyhow::Error> for BuildFailure {
+    fn from(error: anyhow::Error) -> Self {
+        Self { reason: format!("{error:#}"), tests: TestResults::default() }
+    }
+}
+
 /// All builds share one target folder, so they run one at a time.
 pub struct Cargo {
     world: World,