Range<f32> is reflectable but not serializable

Range types can be reflected, but they aren't serializable. I discovered this when trying to serialize `ColorGrading`.

It would be nice if we could just serialize it, but if we can't at least ignore it for internal types like `ColorGrading`.

Start by locating the reflection and serialization entry points for Range and the internal ColorGrading type; the issue names no files or tests. Determine whether Range should serialize generally or whether ColorGrading should be excluded, then add coverage showing the chosen behavior and verify the existing serialization path.

Written by the indexing model from the issue text.