Derive Macro Recall 

#[derive(Recall)]
{
    // Attributes available to this derive:
    #[recallable]
}

Derive macro that generates the Recall trait implementation.

The generated recall method:

• assigns fields directly by default,
• recursively calls recall on fields marked with #[recallable],
• respects #[recallable(skip)] by omitting those fields from recalling.

For #[recallable] fields, replace/merge behavior comes from the field type’s own Recall implementation.